<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD Journal Publishing DTD v2.3 20070202//EN" "journalpublishing.dtd">
<article xml:lang="EN" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article">
<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Cardiovasc. Med.</journal-id>
<journal-title>Frontiers in Cardiovascular Medicine</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Cardiovasc. Med.</abbrev-journal-title>
<issn pub-type="epub">2297-055X</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fcvm.2022.771280</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Cardiovascular Medicine</subject>
<subj-group>
<subject>Original Research</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Increased Rapid Eye Movement Sleep Is Associated With a Reduced Risk of Heart Failure in Middle-Aged and Older Adults</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name><surname>Zhao</surname> <given-names>Binbin</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="author-notes" rid="fn002"><sup>&#x2020;</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1454573/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Jin</surname> <given-names>Xiaoying</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="author-notes" rid="fn002"><sup>&#x2020;</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1723011/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Yang</surname> <given-names>Jian</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1155083/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Ma</surname> <given-names>Qingyan</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1688953/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Yang</surname> <given-names>Zai</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1689090/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Wang</surname> <given-names>Wei</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1257056/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Bai</surname> <given-names>Ling</given-names></name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1454845/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Ma</surname> <given-names>Xiancang</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1454875/overview"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name><surname>Yan</surname> <given-names>Bin</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
<xref ref-type="corresp" rid="c001"><sup>&#x002A;</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/990864/overview"/>
</contrib>
</contrib-group>
<aff id="aff1"><sup>1</sup><institution>Department of Psychiatry, The First Affiliated Hospital of Xi&#x2019;an Jiaotong University</institution>, <addr-line>Xi&#x2019;an</addr-line>, <country>China</country></aff>
<aff id="aff2"><sup>2</sup><institution>Department of Clinical Research Center, The First Affiliated Hospital of Xi&#x2019;an Jiaotong University</institution>, <addr-line>Xi&#x2019;an</addr-line>, <country>China</country></aff>
<aff id="aff3"><sup>3</sup><institution>Department of Cardiology, The First Affiliated Hospital of Xi&#x2019;an Jiaotong University</institution>, <addr-line>Xi&#x2019;an</addr-line>, <country>China</country></aff>
<author-notes>
<fn fn-type="edited-by"><p>Edited by: Tommaso Gori, Johannes Gutenberg University Mainz, Germany</p></fn>
<fn fn-type="edited-by"><p>Reviewed by: Eisuke Amiya, The University of Tokyo Hospital, Japan; Gian Domenico Pinna, Scientific Clinical Institute Maugeri (ICS Maugeri), Italy; Frederic Roche, Universit&#x00E9; Jean Monnet, France</p></fn>
<corresp id="c001">&#x002A;Correspondence: Bin Yan, <email>yanbin.1987@hotmail.com</email></corresp>
<fn fn-type="equal" id="fn002"><p><sup>&#x2020;</sup>These authors have contributed equally to this work</p></fn>
<fn fn-type="other" id="fn004"><p>This article was submitted to Heart Failure and Transplantation, a section of the journal Frontiers in Cardiovascular Medicine</p></fn>
</author-notes>
<pub-date pub-type="epub">
<day>29</day>
<month>03</month>
<year>2022</year>
</pub-date>
<pub-date pub-type="collection">
<year>2022</year>
</pub-date>
<volume>9</volume>
<elocation-id>771280</elocation-id>
<history>
<date date-type="received">
<day>06</day>
<month>09</month>
<year>2021</year>
</date>
<date date-type="accepted">
<day>04</day>
<month>03</month>
<year>2022</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#x00A9; 2022 Zhao, Jin, Yang, Ma, Yang, Wang, Bai, Ma and Yan.</copyright-statement>
<copyright-year>2022</copyright-year>
<copyright-holder>Zhao, Jin, Yang, Ma, Yang, Wang, Bai, Ma and Yan</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/"><p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p></license>
</permissions>
<abstract>
<sec>
<title>Objectives</title>
<p>Rapid eye movement (REM) sleep is closely related to all-cause mortality. The aim of this study is to explore the role of REM sleep on the incident heart failure (HF).</p>
</sec>
<sec>
<title>Methods</title>
<p>We selected 4490 participants (2480 women and 2010 men; mean age, 63.2 &#x00B1; 11.0 years) from the Sleep Heart Health Study. HF was identified as the first occurrence during a mean follow-up period of 10.9 years. REM sleep including percentage of REM sleep and total REM sleep time were monitored using in-home polysomnography at baseline. Multivariable Cox regression analysis was utilized to explore the relationship between REM sleep and HF.</p>
</sec>
<sec>
<title>Results</title>
<p>In total, 436 (9.7%) cases of HF were observed during the entire follow-up period. After adjusting for potential covariates, an increased percentage of REM sleep (per 5%) was independently associated with a reduced incidence of HF [hazard ratio (HR) 0.88, 95% confidence interval (CI) 0.82&#x2013;0.94, <italic>P</italic> &#x003C; 0.001]. A similar result was also found between total REM sleep time (increased per 5 min) and incident HF (HR 0.97, 95% CI 0.95&#x2013;0.99, <italic>P</italic> &#x003C; 0.001). Moreover, the fourth quartile of both percentage of REM sleep (HR 0.65, 95% CI 0.48&#x2013;0.88, <italic>P</italic> = 0.005) and total REM sleep time (HR 0.64, 95% CI 0.45&#x2013;0.90, <italic>P</italic> = 0.010) had lower risk of incident HF when compared with the first quartile.</p>
</sec>
<sec>
<title>Conclusion</title>
<p>An increased percentage of REM sleep and total REM sleep time were associated with a reduced risk of HF. REM sleep may be a predictor of the incident HF.</p>
</sec>
<sec>
<title>Clinical Trial Registration</title>
<p>[<ext-link ext-link-type="uri" xlink:href="https://clinicaltrials.gov">ClinicalTrials.gov</ext-link>], identifier [NCT00005275].</p>
</sec>
</abstract>
<kwd-group>
<kwd>percentage of REM sleep</kwd>
<kwd>total REM sleep time</kwd>
<kwd>sleep heart health study</kwd>
<kwd>polysomnography</kwd>
<kwd>heart failue</kwd>
</kwd-group>
<counts>
<fig-count count="1"/>
<table-count count="3"/>
<equation-count count="0"/>
<ref-count count="31"/>
<page-count count="7"/>
<word-count count="5571"/>
</counts>
</article-meta>
</front>
<body>
<sec id="S1" sec-type="intro">
<title>Introduction</title>
<p>Sleep is an essential physiological phenomenon occurring in alternation with wakefulness, and good quality sleep is vital for maintaining health and homeostasis (<xref ref-type="bibr" rid="B1">1</xref>, <xref ref-type="bibr" rid="B2">2</xref>). According to the World Health Organization, 27% of individuals worldwide suffer from sleep disorders. With the increasing pressure of work, study, and life, sleep issues have severely affected nearly 50&#x2013;70 million people&#x2019;s physical and mental health in the United States (<xref ref-type="bibr" rid="B3">3</xref>). There is growing evidence that poor sleep contributes to cardiovascular disease (CVD) and its risk factors, such as coronary artery disease, stroke, diabetes mellitus, hypertension, and obesity (<xref ref-type="bibr" rid="B4">4</xref>&#x2013;<xref ref-type="bibr" rid="B8">8</xref>). However, the relationship between sleep and CVD deserves further investigation.</p>
<p>Rapid eye movement (REM) sleep and non-REM sleep are two critical stages of sleep. REM sleep, about 20&#x2013;25% of total sleep time, is usually characterized by eye movement, increased heart rate and blood pressure, muscle relaxation, and low voltage and fast frequency in the electroencephalogram (<xref ref-type="bibr" rid="B9">9</xref>, <xref ref-type="bibr" rid="B10">10</xref>). Recently, several studies have shown that individuals with a decreased percentage of REM sleep have high all-cause mortality (<xref ref-type="bibr" rid="B11">11</xref>, <xref ref-type="bibr" rid="B12">12</xref>). Matthews et al. demonstrated that there was a close correlation between the percentage of REM sleep and sleep/wake ratios of blood pressure (<xref ref-type="bibr" rid="B13">13</xref>).</p>
<p>Despite the certainty of knowledge on the effects of REM sleep, the relationship between REM sleep and heart failure (HF) remains unclear. The purpose of this study was to explore whether there is an association between REM sleep (including percentage REM sleep and total REM sleep time) and incident HF based on the Sleep Heart Health Study (SHHS) datasets.</p>
</sec>
<sec id="S2" sec-type="materials|methods">
<title>Materials and Methods</title>
<sec id="S2.SS1">
<title>Study Population</title>
<p>Data were derived based on an existing dataset from the SHHS (<ext-link ext-link-type="uri" xlink:href="https://clinicaltrials.gov">ClinicalTrials.gov</ext-link>, identifier NCT00005275), which was a community-based multicenter prospective cohort study performed by the National Heart, Lung, and Blood Institute to investigate the cardiovascular and other consequences of sleep-disordered breathing between baseline (November 1, 1995 and January 31, 1998) and 2011. The detailed method and design of this study have been reported previously (<xref ref-type="bibr" rid="B14">14</xref>, <xref ref-type="bibr" rid="B15">15</xref>). Briefly, a total of 6441 participants aged 40 years and older were recruited from several &#x201C;parent&#x201D; cohorts including the Atherosclerosis Risk in Communities study, the Cardiovascular Health Study, the Framingham Offspring and Omni study, the Strong Heart Study, the Health and Environment and Tucson Epidemiologic Study, and studies of hypertension in New York. All participants in the SHHS signed written consent, and the study protocol was approved by the institutional review board of each participating institution to collect sleep and questionnaire data. The data underlying this article are available in National Sleep Research Resource, at <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.25822/ghy8-ks59">https://doi.org/10.25822/ghy8-ks59</ext-link>. The datasets were derived from sources in the public domain. Our access to the SHHS database was provided after acquiring a signed agreement with the Brigham and Women&#x2019;s Hospital. The SHHS shared dataset from the National Sleep Research Resource does not include 637 individuals from the Strong Heart Study due to sovereignty issues. Exclusion criteria for our study were (1) previous CVD outcomes (<italic>n</italic> = 535); (2) participants who use CPAP or a mouthpiece (<italic>n</italic> = 7); and (3) no follow-up data (<italic>n</italic> = 772). Finally, 4490 participants were included in the present study (<xref ref-type="supplementary-material" rid="FS1">Supplementary Figure 1</xref>).</p>
</sec>
<sec id="S2.SS2">
<title>Sleep Parameters</title>
<p>Polysomnography (PSG) is essential for the diagnosis and management of many sleep parameters. All individuals in the current study underwent electroencephalography-based overnight unattended PSG (P-Series, Compumedics, Abbotsville, VIC, Australia) at home (<xref ref-type="bibr" rid="B15">15</xref>). Supplementary Material showed the details regarding the specific technical aspects of the PSG measurement. The time and percentage of REM sleep were captured using PSG monitoring. In addition, the percentage of REM sleep was categorized into quartiles: Q1 (&#x003C;15.8%; <italic>n</italic> = 1113), Q2 (15.8&#x2013;20.1%; <italic>n</italic> = 1134), Q3 (20.2&#x2013;24.0%; <italic>n</italic> = 1145), and Q4 (&#x003E;24.0%; <italic>n</italic> = 1098). Moreover, total REM sleep time was also divided into quartiles: Q1 (&#x003C;54.0 min; <italic>n</italic> = 1113), Q2 (54.0&#x2013;73.5 min; <italic>n</italic> = 1162), Q3 (73.6&#x2013;91.5 min; <italic>n</italic> = 1110), and Q4 (&#x003E;91.5 min; <italic>n</italic> = 1105). Other sleep structure parameters, including time in stage 1 (min), time in stage 2 (min), time in stage 3 (min), percentage stage 1, percentage stage 2, and percentage stage 3, were also included in the current analysis. Sleep duration was defined as the total time in bed (Time from lights off to lights on, rounded to nearest minute) based on the PSG record. The apnea&#x2013;hypopnea index (AHI) obtained from the PSG was identified as the number of apneas or hypopneas recorded during the study per hour of sleep, accompanied by at least a 4% drop in oxygen saturation (<xref ref-type="bibr" rid="B15">15</xref>).</p>
</sec>
<sec id="S2.SS3">
<title>The Identification of Heart Failure</title>
<p>The criteria for HF was based on clinical signs and symptoms (such as rales, edema, dyspnea, and orthopnea), physiologic tests (decreased systolic function), and supportive findings (chest radiography or functional cardiac imaging), as previous study reported (<xref ref-type="bibr" rid="B16">16</xref>). HF was defined as the first occurrence during the average 10.9 years&#x2019; follow-up. The control group for HF patients was defined as participants who had no CVD outcomes at baseline and did not develop HF during the follow-up period when investigated the association between REM sleep and HF. Myocardial infarction (MI), stroke, and CVD death were also identified in the follow-up time. All the CVD events were evaluated in the parent cohorts using explicit protocols and identified for SHHS using follow-up interviews, written annual questionnaires, telephone contacts with study participants or next-of-kin, surveillance of local hospital records and community obituaries, and linkage with the Social Security Administration Death Master File (<xref ref-type="bibr" rid="B17">17</xref>).</p>
</sec>
<sec id="S2.SS4">
<title>Covariates</title>
<p>Covariates including age, sex, race, education, marital status, smoking status, body mass index (BMI), alcohol use, caffeine use, benzodiazepine use, hypertension, diabetes mellitus, triglyceride, cholesterol and high-density lipoprotein (HDL) cholesterol, percent time below oxygen desaturation 90% (T90), and AHI were obtained from the SHHS baseline examination.</p>
</sec>
<sec id="S2.SS5">
<title>Statistical Analyses</title>
<p>Continuous and categorical variables were summarized using Student&#x2019;s <italic>t</italic>-test and Chi-squared tests, respectively. The results are presented as mean (&#x00B1;SD) and number (percentages). Moreover, unadjusted Kaplan&#x2013;Meier survival curves were drawn to investigate the overall survival of individuals with different REM sleep quartiles. Cox regression analysis was used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) in the relationship between REM sleep and HF. Multivariable Cox regression analysis adjusted for age, sex, race, education, marital status, smoking status, BMI, alcohol use, caffeine use, benzodiazepine use, hypertension, diabetes mellitus, triglyceride, cholesterol, HDL, sleep duration, T90, and AHI to examine the associations between REM sleep and HF. Subgroup analysis stratified by sex (men vs. women) and AHI (&#x2265;15 vs. &#x003C;15 events/h) was performed when explore the role of REM sleep on the incidence of HF. All statistical analyses were conducted using SPSS (version 24.0; SPSS Inc.). A two-sided <italic>P</italic> &#x003C; 0.05 was considered to be statistically significant.</p>
</sec>
</sec>
<sec id="S3" sec-type="results">
<title>Results</title>
<sec id="S3.SS1">
<title>Study Population</title>
<p><xref ref-type="table" rid="T1">Table 1</xref> shows the study characteristics in participants with and without HF. The present study included 4490 individuals [2480 women (55.2%)] with a mean age of 63.8 &#x00B1; 11.0 years. A total of 436 (9.7%) cases of HF was observed during the follow-up period. Individuals with HF were older and had more smokers, hypertension, diabetes mellitus than controls. In addition, HF patients had low level of percentage of REM sleep, total REM sleep time, T90, and AHI compared with controls.</p>
<table-wrap position="float" id="T1">
<label>TABLE 1</label>
<caption><p>Study characteristics in participants with and without HF.</p></caption>
<table cellspacing="5" cellpadding="5" frame="hsides" rules="groups">
<thead>
<tr>
<td valign="top" align="left">Characteristics</td>
<td valign="top" align="center">Total <italic>n</italic> = 4490</td>
<td valign="top" align="center">HF <italic>n</italic> = 436</td>
<td valign="top" align="center">Controls <italic>n</italic> = 4054</td>
<td valign="top" align="center"><italic>P</italic>-value</td>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Age, years</td>
<td valign="top" align="center">63.2 &#x00B1; 11.0</td>
<td valign="top" align="center">73.6 &#x00B1; 7.8</td>
<td valign="top" align="center">62.1 &#x00B1; 10.7</td>
<td valign="top" align="center">&lt;0.001</td>
</tr>
<tr>
<td valign="top" align="left">Sex (%)</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center">0.035</td>
</tr>
<tr>
<td valign="top" align="left">Men</td>
<td valign="top" align="center">2010 (44.8)</td>
<td valign="top" align="center">216 (49.5)</td>
<td valign="top" align="center">1794 (44.3)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Women</td>
<td valign="top" align="center">2480 (55.2)</td>
<td valign="top" align="center">220 (50.5)</td>
<td valign="top" align="center">2260 (56.7)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Race (%)</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center">0.751</td>
</tr>
<tr>
<td valign="top" align="left">White</td>
<td valign="top" align="center">3904 (87.0)</td>
<td valign="top" align="center">377 (86.5)</td>
<td valign="top" align="center">3527 (87.0)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Others</td>
<td valign="top" align="center">586 (13.0)</td>
<td valign="top" align="center">59 (13.5)</td>
<td valign="top" align="center">527 (13.0)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Education (%)</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center">&lt;0.001</td>
</tr>
<tr>
<td valign="top" align="left">&#x2264;15 years</td>
<td valign="top" align="center">2564 (62.9)</td>
<td valign="top" align="center">316 (74.2)</td>
<td valign="top" align="center">2248 (61.6)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">&#x003E;15 years</td>
<td valign="top" align="center">1511 (37.1)</td>
<td valign="top" align="center">110 (25.8)</td>
<td valign="top" align="center">1401 (38.4)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Marry (%)</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center">&lt;0.001</td>
</tr>
<tr>
<td valign="top" align="left">Married</td>
<td valign="top" align="center">3548 (80.3)</td>
<td valign="top" align="center">314 (72.4)</td>
<td valign="top" align="center">3234 (81.2)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Others</td>
<td valign="top" align="center">870 (19.7)</td>
<td valign="top" align="center">120 (27.6)</td>
<td valign="top" align="center">750 (18.8)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Smoking status, <italic>n</italic> (%)</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center">0.023</td>
</tr>
<tr>
<td valign="top" align="left">Current smoker</td>
<td valign="top" align="center">440 (9.9)</td>
<td valign="top" align="center">45 (10.4)</td>
<td valign="top" align="center">395 (9.8)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Former smoker</td>
<td valign="top" align="center">1925 (43.0)</td>
<td valign="top" align="center">211 (48.6)</td>
<td valign="top" align="center">1714 (42.4)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Never smoker</td>
<td valign="top" align="center">2112 (47.1)</td>
<td valign="top" align="center">178 (41.0)</td>
<td valign="top" align="center">1934 (47.8)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">BMI, kg/m<sup>2</sup></td>
<td valign="top" align="center">28.3 &#x00B1; 5.0</td>
<td valign="top" align="center">29.0 &#x00B1; 4.9</td>
<td valign="top" align="center">28.2 &#x00B1; 5.0</td>
<td valign="top" align="center">0.003</td>
</tr>
<tr>
<td valign="top" align="left">Hypertension, <italic>n</italic> (%)</td>
<td valign="top" align="center">1633 (36.4)</td>
<td valign="top" align="center">282 (64.7)</td>
<td valign="top" align="center">1351 (33.3)</td>
<td valign="top" align="center">&lt;0.001</td>
</tr>
<tr>
<td valign="top" align="left">Diabetes mellitus, <italic>n</italic> (%)</td>
<td valign="top" align="center">286 (6.5)</td>
<td valign="top" align="center">79 (18.4)</td>
<td valign="top" align="center">207 (5.2)</td>
<td valign="top" align="center">&lt;0.001</td>
</tr>
<tr>
<td valign="top" align="left">Alcohol use, <italic>n</italic> (%)</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center">0.001</td>
</tr>
<tr>
<td valign="top" align="left">At least one drink per day</td>
<td valign="top" align="center">1838 (43.7)</td>
<td valign="top" align="center">154 (35.8)</td>
<td valign="top" align="center">1684 (44.6)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">None</td>
<td valign="top" align="center">2369 (56.3)</td>
<td valign="top" align="center">276 (64.2)</td>
<td valign="top" align="center">2093 (55.4)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Caffeine use, <italic>n</italic> (%)</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center">0.010</td>
</tr>
<tr>
<td valign="top" align="left">At least one intake per day</td>
<td valign="top" align="center">2749 (61.3)</td>
<td valign="top" align="center">242 (55.6)</td>
<td valign="top" align="center">2507 (62.0)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">None</td>
<td valign="top" align="center">1732 (38.7)</td>
<td valign="top" align="center">193 (44.4)</td>
<td valign="top" align="center">1539 (38.0)</td>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">Benzodiazepine use, <italic>n</italic> (%)</td>
<td valign="top" align="center">241 (5.4)</td>
<td valign="top" align="center">33 (7.6)</td>
<td valign="top" align="center">208 (5.1)</td>
<td valign="top" align="center">0.030</td>
</tr>
<tr>
<td valign="top" align="left">Triglyceride, mL/dL</td>
<td valign="top" align="center">150.2 &#x00B1; 99.4</td>
<td valign="top" align="center">155.7 &#x00B1; 93.0</td>
<td valign="top" align="center">149.6 &#x00B1; 100.1</td>
<td valign="top" align="center">0.231</td>
</tr>
<tr>
<td valign="top" align="left">Cholesterol, mL/dL</td>
<td valign="top" align="center">206.9 &#x00B1; 38.1</td>
<td valign="top" align="center">204.6 &#x00B1; 38.5</td>
<td valign="top" align="center">207.1 &#x00B1; 38.0</td>
<td valign="top" align="center">0.194</td>
</tr>
<tr>
<td valign="top" align="left">HDL, mL/dL</td>
<td valign="top" align="center">51.1 &#x00B1; 15.8</td>
<td valign="top" align="center">49.4 &#x00B1; 13.8</td>
<td valign="top" align="center">51.3 &#x00B1; 16.0</td>
<td valign="top" align="center">0.007</td>
</tr>
<tr>
<td valign="top" align="left">Sleep duration, h</td>
<td valign="top" align="center">7.3 &#x00B1; 0.9</td>
<td valign="top" align="center">7.3 &#x00B1; 1.0</td>
<td valign="top" align="center">7.3 &#x00B1; 0.9</td>
<td valign="top" align="center">0.849</td>
</tr>
<tr>
<td valign="top" align="left">AHI, events/h</td>
<td valign="top" align="center">9.7 &#x00B1; 13.0</td>
<td valign="top" align="center">12.1 &#x00B1; 13.1</td>
<td valign="top" align="center">9.5 &#x00B1; 13.0</td>
<td valign="top" align="center">&lt;0.001</td>
</tr>
<tr>
<td valign="top" align="left">T90, %</td>
<td valign="top" align="center">3.3 &#x00B1; 9.9</td>
<td valign="top" align="center">5.5 &#x00B1; 13.5</td>
<td valign="top" align="center">3.0 &#x00B1; 9.4</td>
<td valign="top" align="center">&lt;0.001</td>
</tr>
<tr>
<td valign="top" align="left"><bold>Sleep structure</bold></td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/></tr>
<tr>
<td valign="top" align="left">REM sleep time (min)</td>
<td valign="top" align="center">72.4 &#x00B1; 29.0</td>
<td valign="top" align="center">62.7 &#x00B1; 28.3</td>
<td valign="top" align="center">73.4 &#x00B1; 28.9</td>
<td valign="top" align="center">&lt;0.001</td>
</tr>
<tr>
<td valign="top" align="left">Time in stage 1 (min)</td>
<td valign="top" align="center">18.7 &#x00B1; 13.1</td>
<td valign="top" align="center">20.0 &#x00B1; 15.0</td>
<td valign="top" align="center">18.6 &#x00B1; 12.9</td>
<td valign="top" align="center">0.061</td>
</tr>
<tr>
<td valign="top" align="left">Time in stage 2 (min)</td>
<td valign="top" align="center">208.6 &#x00B1; 56.8</td>
<td valign="top" align="center">205.3 &#x00B1; 60.5</td>
<td valign="top" align="center">208.9 &#x00B1; 56.4</td>
<td valign="top" align="center">0.204</td>
</tr>
<tr>
<td valign="top" align="left">Time in stage 3 (min)</td>
<td valign="top" align="center">65.2 &#x00B1; 44.4</td>
<td valign="top" align="center">60.7 &#x00B1; 47.4</td>
<td valign="top" align="center">65.7 &#x00B1; 44.0</td>
<td valign="top" align="center">0.027</td>
</tr>
<tr>
<td valign="top" align="left">REM sleep time (%)</td>
<td valign="top" align="center">19.6 &#x00B1; 6.7</td>
<td valign="top" align="center">17.7 &#x00B1; 7.2</td>
<td valign="top" align="center">19.8 &#x00B1; 6.7</td>
<td valign="top" align="center">&lt;0.001</td>
</tr>
<tr>
<td valign="top" align="left">Time in stage 1 (%)</td>
<td valign="top" align="center">5.2 &#x00B1; 3.8</td>
<td valign="top" align="center">5.8 &#x00B1; 4.5</td>
<td valign="top" align="center">5.2 &#x00B1; 3.8</td>
<td valign="top" align="center">0.004</td>
</tr>
<tr>
<td valign="top" align="left">Time in stage 2 (%)</td>
<td valign="top" align="center">57.3 &#x00B1; 13.1</td>
<td valign="top" align="center">59.1 &#x00B1; 14.1</td>
<td valign="top" align="center">57.1 &#x00B1; 12.9</td>
<td valign="top" align="center">0.005</td>
</tr>
<tr>
<td valign="top" align="left">Time in stage 3 (%)</td>
<td valign="top" align="center">17.9 &#x00B1; 11.9</td>
<td valign="top" align="center">17.3 &#x00B1; 12.7</td>
<td valign="top" align="center">17.9 &#x00B1; 11.8</td>
<td valign="top" align="center">0.348</td>
</tr>
<tr>
<td valign="top" align="left">Follow-up time, years</td>
<td valign="top" align="center">10.9 &#x00B1; 2.8</td>
<td valign="top" align="center">9.4 &#x00B1; 3.0</td>
<td valign="top" align="center">11.1 &#x00B1; 2.7</td>
<td valign="top" align="center">&lt;0.001</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn><p><italic>AHI, apnea&#x2013;hypopnea index; BMI, body mass index; HDL, high-density lipoprotein; HF, heart failure; REM, rapid eye movement; T90, percent time below oxygen desaturation 90%. Results are presented as mean &#x00B1; SD or number (percentage). The P-values represent the difference between two groups.</italic></p></fn>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="S3.SS2">
<title>The Relationship Between Rapid Eye Movement Sleep and Incident Heart Failure</title>
<p>Unadjusted Kaplan&#x2013;Meier survival curves showed that HF event rates increased with a decrease in REM sleep percentage (<xref ref-type="fig" rid="F1">Figure 1A</xref>; Log-rank test: <italic>P</italic> &#x003C; 0.001). After adjusting for age, sex, race, education, marital status, smoking status, BMI, alcohol use, caffeine use, benzodiazepine use, hypertension, diabetes mellitus, triglyceride, cholesterol, HDL, sleep duration, T90, and AHI (natural log-transformed), multivariable Cox regression analysis showed that an elevated percentage of REM sleep (per 5%) was significantly associated with a reduced risk of HF (HR 0.88, 95% CI 0.82&#x2013;0.94, <italic>P</italic> &#x003C; 0.001). Moreover, individuals in the fourth quartile of percentage REM sleep had a significantly lower risk of HF than those in the first quartile (HR 0.65, 95% CI 0.48&#x2013;0.88, <italic>P</italic> = 0.005) (<xref ref-type="table" rid="T2">Table 2</xref>).</p>
<fig id="F1" position="float">
<label>FIGURE 1</label>
<caption><p>Kaplan&#x2013;Meier plots of overall survival for HF stratified by percentage REM sleep quartiles [<bold>(A)</bold> Q1: &#x003C;15.8%; Q2: 15.8&#x2013;20.1%; Q3: 20.2&#x2013;24.0%; Q4: &#x003E;24.0%] and total REM sleep time quartiles [<bold>(B)</bold> Q1: &#x003C;54.0 min; Q2: 54.0&#x2013;73.5 min; Q3: 73.6&#x2013;91.5 min; Q4: &#x003E;91.5 min].</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcvm-09-771280-g001.tif"/>
</fig>
<table-wrap position="float" id="T2">
<label>TABLE 2</label>
<caption><p>Hazard ratios and 95% CIs for REM sleep associated with incident HF.</p></caption>
<table cellspacing="5" cellpadding="5" frame="hsides" rules="groups">
<thead>
<tr>
<td valign="top" align="left">REM sleep traits</td>
<td valign="top" align="center">Persons (<italic>n</italic>)</td>
<td valign="top" align="center">Event, <italic>n</italic> (%)</td>
<td valign="top" align="center" colspan="2">Univariable model</td>
<td valign="top" align="center" colspan="2">Age and gender adjusted</td>
<td valign="top" align="center" colspan="2">Multivariable adjusted</td>
</tr>
<tr>
<td valign="top" align="left"><hr/></td>
<td valign="top" align="center"><hr/></td>
<td valign="top" align="center"><hr/></td>
<td valign="top" align="center" colspan="2"><hr/></td>
<td valign="top" align="center" colspan="2"><hr/></td>
<td valign="top" align="center" colspan="2"><hr/></td>
</tr>
<tr>
<td valign="top" align="left">Percentage REM sleep</td>
<td valign="top" align="center">4490</td>
<td valign="top" align="center">436 (9.7)</td>
<td valign="top" align="center">HR (95% CI)</td>
<td valign="top" align="center"><italic>P</italic></td>
<td valign="top" align="center">HR (95% CI)</td>
<td valign="top" align="center"><italic>P</italic></td>
<td valign="top" align="center">HR (95% CI)</td>
<td valign="top" align="center"><italic>P</italic></td>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Q4 (&#x003E;24.0%)</td>
<td valign="top" align="center">1098</td>
<td valign="top" align="center">148 (13.5)</td>
<td valign="top" align="center">0.44 (0.33&#x2013;0.58)</td>
<td valign="top" align="center">&lt;0.001</td>
<td valign="top" align="center">0.57 (0.43&#x2013;0.76)</td>
<td valign="top" align="center">&lt;0.001</td>
<td valign="top" align="center">0.65 (0.48&#x2013;0.88)</td>
<td valign="top" align="center">0.005</td>
</tr>
<tr>
<td valign="top" align="left">Q3 (20.2&#x2013;24.0%)</td>
<td valign="top" align="center">1145</td>
<td valign="top" align="center">126 (11.0)</td>
<td valign="top" align="center">0.55 (0.43&#x2013;0.72)</td>
<td valign="top" align="center">&lt;0.001</td>
<td valign="top" align="center">0.67 (0.51&#x2013;0.86)</td>
<td valign="top" align="center">0.002</td>
<td valign="top" align="center">0.78 (0.59&#x2013;1.04)</td>
<td valign="top" align="center">0.087</td>
</tr>
<tr>
<td valign="top" align="left">Q2 (15.8&#x2013;20.1%)</td>
<td valign="top" align="center">1134</td>
<td valign="top" align="center">91 (8.0)</td>
<td valign="top" align="center">0.78 (0.61&#x2013;0.98)</td>
<td valign="top" align="center">0.036</td>
<td valign="top" align="center">0.87 (0.69&#x2013;1.10)</td>
<td valign="top" align="center">0.253</td>
<td valign="top" align="center">1.07 (0.84&#x2013;1.38)</td>
<td valign="top" align="center">0.577</td>
</tr>
<tr>
<td valign="top" align="left">Q1 (&#x003C;15.8%)</td>
<td valign="top" align="center">1113</td>
<td valign="top" align="center">71 (6.4)</td>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center"/>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center"/>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Continuous (per 5%)</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center">0.80 (0.75&#x2013;0.85)</td>
<td valign="top" align="center">&lt;0.001</td>
<td valign="top" align="center">0.85 (0.80&#x2013;0.91)</td>
<td valign="top" align="center">&lt;0.001</td>
<td valign="top" align="center">0.88 (0.82&#x2013;0.94)</td>
<td valign="top" align="center">&lt;0.001</td>
</tr>
<tr>
<td valign="top" align="left">Total REM sleep time</td>
<td valign="top" align="center">4490</td>
<td valign="top" align="center">436 (9.7)</td>
<td valign="top" align="center">HR (95% CI)</td>
<td valign="top" align="center"><italic>P</italic></td>
<td valign="top" align="center">HR (95% CI)</td>
<td valign="top" align="center"><italic>P</italic></td>
<td valign="top" align="center">HR (95% CI)</td>
<td valign="top" align="center"><italic>P</italic></td>
</tr>
<tr>
<td valign="top" align="left">Q4 (&#x003E;91.5 min)</td>
<td valign="top" align="center">1105</td>
<td valign="top" align="center">149 (13.5)</td>
<td valign="top" align="center">0.37 (0.28&#x2013;0.50)</td>
<td valign="top" align="center">&lt;0.001</td>
<td valign="top" align="center">0.56 (0.42&#x2013;0.76)</td>
<td valign="top" align="center">&lt;0.001</td>
<td valign="top" align="center">0.64 (0.45&#x2013;0.90)</td>
<td valign="top" align="center">0.010</td>
</tr>
<tr>
<td valign="top" align="left">Q3 (73.6&#x2013;91.5 min)</td>
<td valign="top" align="center">1110</td>
<td valign="top" align="center">130 (11.7)</td>
<td valign="top" align="center">0.59 (0.46&#x2013;0.76)</td>
<td valign="top" align="center">&lt;0.001</td>
<td valign="top" align="center">0.71 (0.54&#x2013;0.91)</td>
<td valign="top" align="center">0.008</td>
<td valign="top" align="center">0.79 (0.59&#x2013;1.06)</td>
<td valign="top" align="center">0.107</td>
</tr>
<tr>
<td valign="top" align="left">Q2 (54.0&#x2013;73.5 min)</td>
<td valign="top" align="center">1162</td>
<td valign="top" align="center">95 (8.2)</td>
<td valign="top" align="center">0.78 (0.62&#x2013;0.99)</td>
<td valign="top" align="center">0.041</td>
<td valign="top" align="center">0.85 (0.67&#x2013;1.08)</td>
<td valign="top" align="center">0.179</td>
<td valign="top" align="center">0.94 (0.73&#x2013;1.21)</td>
<td valign="top" align="center">0.611</td>
</tr>
<tr>
<td valign="top" align="left">Q1 (&#x003C;54.0 min)</td>
<td valign="top" align="center">1113</td>
<td valign="top" align="center">62 (5.6)</td>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center"/>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center"/>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Continuous (per 5 min)</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center">0.94 (0.92&#x2013;0.95)</td>
<td valign="top" align="center">&lt;0.001</td>
<td valign="top" align="center">0.96 (0.94&#x2013;0.97)</td>
<td valign="top" align="center">&lt;0.001</td>
<td valign="top" align="center">0.97 (0.95&#x2013;0.99)</td>
<td valign="top" align="center">&lt;0.001</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn><p><italic>95% CI, 95% confidence interval; HF, heart failure; HR, hazard ratio; REM, rapid eye movement sleep. Percentage REM sleep quartiles (Q1: &#x003C;15.8%; Q2: 15.8&#x2013;20.1%; Q3: 20.2&#x2013;24.0%; Q4: &#x003E;24.0%). Total REM sleep time quartiles (Q1: &#x003C;54.0 min; Q2: 54.0&#x2013;73.5 min; Q3: 73.6&#x2013;91.5 min; Q4: &#x003E;91.5 min). The comparison was made in the participants with and without HF. Ref is referred to the first quantile of percentage REM sleep or total REM sleep time. Multivariable Cox regression analysis adjusted by age, sex, race, education, marital status, smoking status, BMI, alcohol use, caffeine use, benzodiazepine use, hypertension, diabetes mellitus, triglyceride, cholesterol, HDL, sleep duration, T90, and AHI (natural log-transformed).</italic></p></fn>
</table-wrap-foot>
</table-wrap>
<p>We also explored the association between total REM sleep time and HF. Similar to the results for REM sleep percentage, total REM sleep time (increased per 5 min) was found to be independently associated with HF (HR 0.97, 95% CI 0.95&#x2013;0.99, <italic>P</italic> &#x003C; 0.001). In addition, individuals in the fourth quartile of the total REM sleep time had the highest overall survival rate (<xref ref-type="fig" rid="F1">Figure 1B</xref>; Log-rank test: <italic>P</italic> &#x003C; 0.001). Total REM sleep time within the fourth quartile was associated with a lower risk of HF (HR 0.64, 95% CI 0.45&#x2013;0.90, <italic>P</italic> = 0.010) than in the first quartile (<xref ref-type="table" rid="T2">Table 2</xref>). We also showed the results of final fully adjusted model in our <xref ref-type="supplementary-material" rid="TS1">Supplementary Tables 1</xref>, <xref ref-type="supplementary-material" rid="TS1">2</xref>.</p>
</sec>
<sec id="S3.SS3">
<title>The Association of Rapid Eye Movement Sleep With Myocardial Infarction, Stroke, and Cardiovascular Disease Death</title>
<p>During the follow-up time, 282 cases of MI, 201 cases of stroke, and 238 cases of CVD death occurred. We also explored role of percentage REM sleep and total REM sleep time on the incidence of MI, stroke, and CVD death. Both percentage REM sleep (HR 0.90, 95% CI 0.81&#x2013;0.99, <italic>P</italic> = 0.032) and total REM sleep time (HR 0.97, 95% CI 0.94&#x2013;0.99, <italic>P</italic> = 0.010) were associated with decreased risk of CVD death, but not associated with MI and stroke (<xref ref-type="table" rid="T3">Table 3</xref>).</p>
<table-wrap position="float" id="T3">
<label>TABLE 3</label>
<caption><p>Hazard ratios and 95% CIs for REM sleep associated with MI, stroke, and CVD death.</p></caption>
<table cellspacing="5" cellpadding="5" frame="hsides" rules="groups">
<thead>
<tr>
<td valign="top" align="left"/>
<td valign="top" align="left"/>
<td valign="top" align="center"/>
<td valign="top" align="center" colspan="4">REM sleep quartiles<hr/></td>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">REM traits</td>
<td valign="top" align="left">CVD events</td>
<td valign="top" align="center">Event, <italic>n</italic> (%)</td>
<td valign="top" align="center">Q1 (low)</td>
<td valign="top" align="center">Q2</td>
<td valign="top" align="center">Q3</td>
<td valign="top" align="center">Q4 (high)</td>
<td valign="top" align="center">Overall trend (per 5 unit)</td>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Percentage REM sleep (%)</td>
<td valign="top" align="left">MI</td>
<td valign="top" align="center">282 (6.3)</td>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center">1.03 (0.72&#x2013;1.46)</td>
<td valign="top" align="center">0.98 (0.68&#x2013;1.41)</td>
<td valign="top" align="center">0.98 (0.67&#x2013;1.41)</td>
<td valign="top" align="center">1.01 (0.92&#x2013;1.11)</td>
</tr>
<tr>
<td valign="top" align="left"/>
<td valign="top" align="left">Stroke</td>
<td valign="top" align="center">201 (4.5)</td>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center">0.86 (0.58&#x2013;1.29)</td>
<td valign="top" align="center">0.72 (0.47&#x2013;1.11)</td>
<td valign="top" align="center">0.90 (0.60&#x2013;1.36)</td>
<td valign="top" align="center">0.95 (0.85&#x2013;1.05)</td>
</tr>
<tr>
<td valign="top" align="left"/>
<td valign="top" align="left">CVD death</td>
<td valign="top" align="center">238 (5.3)</td>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center">0.75 (0.52&#x2013;1.08)</td>
<td valign="top" align="center">0.72 (0.49&#x2013;1.07)</td>
<td valign="top" align="center">0.74 (0.50&#x2013;1.09)</td>
<td valign="top" align="center">0.90 (0.81&#x2013;0.99) <xref ref-type="table-fn" rid="t3fns1">&#x002A;</xref></td>
</tr>
<tr>
<td valign="top" align="left">Total REM sleep time (min)</td>
<td valign="top" align="left">MI</td>
<td valign="top" align="center">282 (6.3)</td>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center">0.93 (0.65&#x2013;1.33)</td>
<td valign="top" align="center">1.05 (0.72&#x2013;1.52)</td>
<td valign="top" align="center">1.09 (0.71&#x2013;1.65)</td>
<td valign="top" align="center">1.00 (0.98&#x2013;1.03)</td>
</tr>
<tr>
<td valign="top" align="left"/>
<td valign="top" align="left">Stroke</td>
<td valign="top" align="center">201 (4.5)</td>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center">0.75 (0.50&#x2013;1.12)</td>
<td valign="top" align="center">0.78 (0.51&#x2013;1.21)</td>
<td valign="top" align="center">0.75 (0.46&#x2013;1.22)</td>
<td valign="top" align="center">0.98 (0.96&#x2013;1.01)</td>
</tr>
<tr>
<td valign="top" align="left"/>
<td valign="top" align="left">CVD death</td>
<td valign="top" align="center">238 (5.3)</td>
<td valign="top" align="center">1 (Ref)</td>
<td valign="top" align="center">0.78 (0.54&#x2013;1.12)</td>
<td valign="top" align="center">0.74 (0.50&#x2013;1.10)</td>
<td valign="top" align="center">0.71 (0.45&#x2013;1.11)</td>
<td valign="top" align="center">0.97 (0.94&#x2013;0.99)<xref ref-type="table-fn" rid="t3fns1"><sup>#</sup></xref></td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn><p><italic>95% CI, 95% confidence interval; CVD, cardiovascular disease; HR, hazard ratio; MI, myocardial infarction; REM, rapid eye movement sleep. Percentage REM sleep quartiles (Q1: &#x003C;15.8%; Q2: 15.8&#x2013;20.1%; Q3: 20.2&#x2013;24.0%; Q4: &#x003E;24.0%). Total REM sleep time quartiles (Q1: &#x003C;54.0 min; Q2: 54.0&#x2013;73.5 min; Q3: 73.6&#x2013;91.5 min; Q4: &#x003E;91.5 min). The comparison was made in the participants with and without individual CVD events (MI, stroke, and CVD death), respectively. Ref is referred to the first quantile of percentage REM sleep or total REM sleep time. Multivariable Cox regression analysis adjusted by age, sex, race, education, marital status, smoking status, BMI, alcohol use, caffeine use, benzodiazepine use, hypertension, diabetes mellitus, triglyceride, cholesterol, HDL, sleep duration, T90, and AHI (natural log-transformed).</italic></p></fn>
<fn id="t3fns1"><p><italic>&#x002A;P &#x003C; 0.05; <sup>#</sup>P &#x003C; 0.01.</italic></p></fn>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="S3.SS4">
<title>Other Sleep Structure Parameters and Cardiovascular Disease Events</title>
<p>We also investigated the role of sleep characteristics (including time in stage 1, time in stage 2, time in stage 3, percentage stage 1, percentage stage 2, and percentage stage 1) on the incidence of HF, MI, stroke, and CVD death. No significant association was found after adjusting for potential confounding variables (<xref ref-type="supplementary-material" rid="TS1">Supplementary Table 3</xref>).</p>
</sec>
<sec id="S3.SS5">
<title>Subgroup Analysis</title>
<p>We further conducted subgroup analysis stratified by AHI &#x2265; 15 and AHI &#x003C; 15 events/h and sex (men vs. women) to further explore the role of REM sleep percentage and total REM sleep time on the incidence of HF. The results showed that both percentage and total time of REM sleep were still associated with incident HF in these subgroup analyses (<xref ref-type="supplementary-material" rid="TS1">Supplementary Tables 4</xref>, <xref ref-type="supplementary-material" rid="TS1">5</xref>). Moreover, no significant interaction was found in these analyses (all the <italic>P</italic><sub><italic>interaction</italic></sub> &#x003E; 0.05).</p>
</sec>
</sec>
<sec id="S4" sec-type="discussion">
<title>Discussion</title>
<p>In the present study, we utilized a large-scale community-based population from SHHS to investigate the association between REM sleep and incidence of HF. Our study was a cohort-study design and the comparison of percentage REM sleep and total REM sleep time was made in the individuals with and without HF. REM sleep traits including percentage REM sleep and total REM sleep time were monitored by over-night PSG at home. Our multivariable Cox regression analysis demonstrated that middle-aged and older adults with an elevated percentage of REM sleep and total REM sleep time had a reduced risk of incident HF.</p>
<p>Poor lifestyles and behaviors are considered the main causes of negative cardiovascular outcomes (<xref ref-type="bibr" rid="B18">18</xref>). Sleep, a basic human behavior, is believed to be related to the risk of CVD and other health outcomes (<xref ref-type="bibr" rid="B19">19</xref>, <xref ref-type="bibr" rid="B20">20</xref>). REM sleep is an important aspect of human sleep and often accompanied with vivid dreaming and high level of brain activity, which also has substantial effects on the physiological functions of the individual (<xref ref-type="bibr" rid="B21">21</xref>, <xref ref-type="bibr" rid="B22">22</xref>). Previous studies showed that participants with a depressed mood spent less time in REM sleep (<xref ref-type="bibr" rid="B23">23</xref>). Besides, decreased REM sleep time in individuals is found to be closely related to worsening cognitive performance (<xref ref-type="bibr" rid="B24">24</xref>, <xref ref-type="bibr" rid="B25">25</xref>). Matthews et al. also demonstrated a significant correlation between a lower proportion of REM sleep and a greater sleep/wake ratio of blood pressure (<xref ref-type="bibr" rid="B13">13</xref>). Increasing evidences have shown that REM sleep is vital to human health, but there was no evidence regarding the role of REM sleep on the incident HF. In this study, we provided evidences that both increased percentage REM sleep and total REM sleep time were significantly associated with low risk of incident HF. Sleep disordered breathing (SDB) is characterized by abnormal respiration during sleep and may influence the sleep continuity (<xref ref-type="bibr" rid="B26">26</xref>). SDB was also closely related to an increased risk of incident HF (<xref ref-type="bibr" rid="B27">27</xref>). Azarbarzin et al. found that sleep apnea-specific hypoxic burden was associated with the HF risk (<xref ref-type="bibr" rid="B28">28</xref>). We therefore adjusted AHI and T90 in our multivariable Cox regression analysis. Moreover, we performed subgroup analysis stratified by SDB severity (AHI &#x2265; 15 vs. AHI &#x003C; 15 events/h) to examine whether SDB was potential confounders in the relationship between REM sleep and HF. The results revealed that percentage REM sleep and total REM sleep time were still associated with incidence of HF in subgroup analysis. Our findings indicated that REM sleep traits including percentage REM sleep and total REM sleep time might be marker to predict incident HF.</p>
<p>Previous studies showed that REM sleep is associated with all-cause mortality (<xref ref-type="bibr" rid="B11">11</xref>, <xref ref-type="bibr" rid="B12">12</xref>). A decreased percentage of REM sleep was found to be associated with high CVD mortality in the Outcomes of Sleep Disorders in Older Men (MrOS) Sleep Study Cohort, but this relationship was not found in the Wisconsin Sleep Cohort (<xref ref-type="bibr" rid="B12">12</xref>). We also explored the role of REM sleep on the MI, stroke, and CVD death. Our results found a significant association of both percentage of REM sleep and total REM sleep time with CVD death based on SHHS, which could support the results of MrOS. However, no significant association was found between REM sleep and incidence of MI and stroke.</p>
<p>Previous studies revealed that the initiation and maintenance of REM sleep was related to the brainstem, forebrain, and hypothalamus (<xref ref-type="bibr" rid="B29">29</xref>). Gonnissen et al. showed that the changes of REM sleep time could be caused by circadian misalignment. Besides, reduced REM sleep may be associated with HPA-axis dysregulation and decreased insulin sensitivity (<xref ref-type="bibr" rid="B30">30</xref>). Additionally, decreased REM sleep was also found to have a high cortisol concentration (<xref ref-type="bibr" rid="B31">31</xref>). We speculate that the abnormal circadian rhythm and neuroendocrine function may contribute to the increased risk of CHF. The underlying biological mechanisms of REM sleep leading to an increased risk of HF still deserved further investigation.</p>
<p>The current study has some strengths. To our knowledge, it is the first to investigate the effect of REM sleep on the incidence of HF. REM sleep, including percentage and total time, was objectively monitored using PSG records, and our findings were based on a large community-based population. Nevertheless, this study also has several limitations. The objects of our analysis were mostly middle-aged and older Caucasian adults; therefore, the generalization of our conclusions to young people and other races merits careful consideration. Second, objective REM sleep was evaluated using a single-night PSG and may not fully reflect the significant value of REM sleep. Multiple long-term PSG monitoring may provide more accurate sleep parameters. Third, several parent cohorts oversampled snorers to increase the study-wide prevalence of SDB in SHHS. Therefore, our study population could not represent the general community population. Finally, we lack of data such as B-type natriuretic peptide (BNP), kidney function and left ventricular parameters such as ejection fraction, end-diastolic volume and end-systolic volume in the SHHS database that is closely related to the HF. We will investigate the effect of REM sleep on the changes of BNP, renal function and left ventricular function in our following study.</p>
</sec>
<sec id="S5" sec-type="conclusion">
<title>Conclusion</title>
<p>Our study provides evidence that increased percentage and total time of REM sleep were associated with a decreased risk of incident HF in middle-aged and older adults. Percentage REM sleep and total REM sleep time may be predictors for the incidence of HF. Monitoring REM sleep to fully understand the nocturnal autonomic nervous activity of people may contribute to prevent HF in the early stages.</p>
</sec>
<sec id="S6" sec-type="data-availability">
<title>Data Availability Statement</title>
<p>The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.25822/ghy8-ks59">https://doi.org/10.25822/ghy8-ks59</ext-link>.</p>
</sec>
<sec id="S7">
<title>Ethics Statement</title>
<p>The studies involving human participants were reviewed and approved by the Boston University, Case Western Reserve University, Johns Hopkins University, Missouri Breaks Research, Inc., New York University Medical Center, University of Arizona, University of California at Davis, University of Minnesota &#x2013; Clinical and Translational Science Institute, and University of Washington. The patients/participants provided their written informed consent to participate in this study.</p>
</sec>
<sec id="S8">
<title>Author Contributions</title>
<p>BY and XM raised the idea for the study and handled the supervision in our study. BZ, XJ, JY, QM, LB, ZY, and WW contributed to the study design, writing, and review of the report. BY acquired the data in SHHS and participated in further data analysis. All authors approved the final version of the report.</p>
</sec>
<sec id="conf1" sec-type="COI-statement">
<title>Conflict of Interest</title>
<p>The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
<sec id="pudiscl1" sec-type="disclaimer">
<title>Publisher&#x2019;s Note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
</sec>
</body>
<back>
<sec id="S9" sec-type="funding-information">
<title>Funding</title>
<p>This study was supported by the Natural Science Basic Research Program of Shaanxi (Nos. 2021JQ-395 and 2020ZDLSF02-10) and the Clinical Research Award of the First Affiliated Hospital of Xi&#x2019;an Jiaotong University, China (No. XJTU1AF-CRF-2019-022). SHHS was supported by the National Heart, Lung, and Blood Institute cooperative agreements U01HL53916 (University of California, Davis), U01HL53931 (New York University), U01HL53934 (University of Minnesota), U01HL53937 and U01HL64360 (Johns Hopkins University), U01HL53938 (University of Arizona), U01HL53940 (University of Washington), U01HL53941 (Boston University), and U01HL63463 (Case Western Reserve University). The National Sleep Research Resource was supported by the National Heart, Lung, and Blood Institute (R24 HL114473 and 75N92019R002). SHHS was particularly grateful to the members of these cohorts who agreed to participate in SHHS as well.</p>
</sec>
<ack>
<p>We appreciate the Brigham and Women&#x2019;s Hospital for sharing the Datasets of Sleep Heart Health Study (SHHS). SHHS recognizes all the investigators and staff who have contributed to its success. A list of SHHS investigators, staff and their participating institutions is available on the SHHS website, <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.25822/ghy8-ks59">https://doi.org/10.25822/ghy8-ks59</ext-link>.</p>
</ack>
<sec id="S11" sec-type="supplementary-material">
<title>Supplementary Material</title>
<p>The Supplementary Material for this article can be found online at: <ext-link ext-link-type="uri" xlink:href="https://www.frontiersin.org/articles/10.3389/fcvm.2022.771280/full#supplementary-material">https://www.frontiersin.org/articles/10.3389/fcvm.2022.771280/full#supplementary-material</ext-link></p>
<supplementary-material xlink:href="Data_Sheet_1.docx" id="DS1" mimetype="application/vnd.openxmlformats-officedocument.wordprocessingml.document" xmlns:xlink="http://www.w3.org/1999/xlink"/>
<supplementary-material xlink:href="Table_1.DOCX" id="TS1" mimetype="application/vnd.openxmlformats-officedocument.wordprocessingml.document" xmlns:xlink="http://www.w3.org/1999/xlink"/>
<supplementary-material xlink:href="Image_1.pdf" id="FS1" mimetype="application/pdf" xmlns:xlink="http://www.w3.org/1999/xlink"/>
</sec>
<ref-list>
<title>References</title>
<ref id="B1"><label>1.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kaufmann</surname> <given-names>T</given-names></name> <name><surname>Elvs&#x00E5;shagen</surname> <given-names>T</given-names></name> <name><surname>Aln&#x00E6;s</surname> <given-names>D</given-names></name> <name><surname>Zak</surname> <given-names>N</given-names></name> <name><surname>Pedersen</surname> <given-names>P&#x00D8;</given-names></name> <name><surname>Norbom</surname> <given-names>LB</given-names></name><etal/></person-group> <article-title>The brain functional connectome is robustly altered by lack of sleep.</article-title> <source><italic>NeuroImage.</italic></source> (<year>2016</year>) <volume>127</volume>:<fpage>324</fpage>&#x2013;<lpage>32</lpage>. <pub-id pub-id-type="doi">10.1016/j.neuroimage.2015.12.028</pub-id> <pub-id pub-id-type="pmid">26712339</pub-id></citation></ref>
<ref id="B2"><label>2.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Ibarra-Coronado</surname> <given-names>EG</given-names></name> <name><surname>Pantaleon-Martinez</surname> <given-names>AM</given-names></name> <name><surname>Velazquez-Moctezuma</surname> <given-names>J</given-names></name> <name><surname>Prosp&#x00E9;ro-Garc&#x00ED;a</surname> <given-names>O</given-names></name> <name><surname>M&#x00E9;ndez-D&#x00ED;az</surname> <given-names>M</given-names></name> <name><surname>P&#x00E9;rez-Tapia</surname> <given-names>M</given-names></name><etal/></person-group> <article-title>The bidirectional relationship between sleep and immunity against infections.</article-title> <source><italic>J Immunol Res.</italic></source> (<year>2015</year>) <volume>2015</volume>:<issue>678164</issue>. <pub-id pub-id-type="doi">10.1155/2015/678164</pub-id> <pub-id pub-id-type="pmid">26417606</pub-id></citation></ref>
<ref id="B3"><label>3.</label><citation citation-type="journal"><collab>Research IoMUCoSMa.</collab> <person-group person-group-type="editor"><name><surname>Colten</surname> <given-names>HR</given-names></name> <name><surname>Altevogt</surname> <given-names>BM</given-names></name></person-group> <role>editors</role>. <source><italic>Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem.</italic></source> <publisher-loc>Washington, DC</publisher-loc>: <publisher-name>National Academies Press (US)</publisher-name> (<year>2006</year>).</citation></ref>
<ref id="B4"><label>4.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Wang</surname> <given-names>C</given-names></name> <name><surname>Bangdiwala</surname> <given-names>S</given-names></name> <name><surname>Rangarajan</surname> <given-names>S</given-names></name> <name><surname>Lear</surname> <given-names>SA</given-names></name> <name><surname>AlHabib</surname> <given-names>KF</given-names></name> <name><surname>Mohan</surname> <given-names>V</given-names></name><etal/></person-group> <article-title>Association of estimated sleep duration and naps with mortality and cardiovascular events: a study of 116 632 people from 21 countries.</article-title> <source><italic>Eur Heart J.</italic></source> (<year>2019</year>) <volume>40</volume>:<fpage>1620</fpage>&#x2013;<lpage>9</lpage>. <pub-id pub-id-type="doi">10.1093/eurheartj/ehy695</pub-id> <pub-id pub-id-type="pmid">30517670</pub-id></citation></ref>
<ref id="B5"><label>5.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Wang</surname> <given-names>Y</given-names></name> <name><surname>Wang</surname> <given-names>J</given-names></name> <name><surname>Chen</surname> <given-names>S</given-names></name> <name><surname>Li</surname> <given-names>JQ</given-names></name> <name><surname>Lu</surname> <given-names>QD</given-names></name> <name><surname>Vitiello</surname> <given-names>MV</given-names></name><etal/></person-group> <article-title>Association of Longitudinal patterns of habitual sleep duration with risk of cardiovascular events and all-cause mortality.</article-title> <source><italic>JAMA Netw Open.</italic></source> (<year>2020</year>) <volume>3</volume>:<issue>e205246</issue>. <pub-id pub-id-type="doi">10.1001/jamanetworkopen.2020.5246</pub-id> <pub-id pub-id-type="pmid">32442289</pub-id></citation></ref>
<ref id="B6"><label>6.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Yan</surname> <given-names>B</given-names></name> <name><surname>Zhao</surname> <given-names>B</given-names></name> <name><surname>Fan</surname> <given-names>Y</given-names></name> <name><surname>Yang</surname> <given-names>J</given-names></name> <name><surname>Zhu</surname> <given-names>F</given-names></name> <name><surname>Chen</surname> <given-names>Y</given-names></name><etal/></person-group> <article-title>The association between sleep efficiency and diabetes mellitus in community-dwelling individuals with or without sleep-disordered breathing.</article-title> <source><italic>J Diabetes.</italic></source> (<year>2020</year>) <volume>12</volume>:<fpage>215</fpage>&#x2013;<lpage>23</lpage>. <pub-id pub-id-type="doi">10.1111/1753-0407.12987</pub-id> <pub-id pub-id-type="pmid">31503406</pub-id></citation></ref>
<ref id="B7"><label>7.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Rosique-Esteban</surname> <given-names>N</given-names></name> <name><surname>Papandreou</surname> <given-names>C</given-names></name> <name><surname>Romaguera</surname> <given-names>D</given-names></name> <name><surname>Warnberg</surname> <given-names>J</given-names></name> <name><surname>Corella</surname> <given-names>D</given-names></name> <name><surname>Mart&#x00ED;nez-Gonz&#x00E1;lez</surname> <given-names>M&#x00C1;</given-names></name><etal/></person-group> <article-title>Cross-sectional associations of objectively-measured sleep characteristics with obesity and type 2 diabetes in the PREDIMED-Plus trial.</article-title> <source><italic>Sleep.</italic></source> (<year>2018</year>) <volume>41</volume>:<issue>zsy190</issue>. <pub-id pub-id-type="doi">10.1093/sleep/zsy190</pub-id> <pub-id pub-id-type="pmid">30285250</pub-id></citation></ref>
<ref id="B8"><label>8.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Li</surname> <given-names>X</given-names></name> <name><surname>Sotres-Alvarez</surname> <given-names>D</given-names></name> <name><surname>Gallo</surname> <given-names>LC</given-names></name> <name><surname>Ramos</surname> <given-names>AR</given-names></name> <name><surname>Aviles-Santa</surname> <given-names>L</given-names></name> <name><surname>Perreira</surname> <given-names>KM</given-names></name><etal/></person-group> <article-title>Associations of sleep-disordered breathing and insomnia with incident hypertension and diabetes. the hispanic community health study/study of latinos.</article-title> <source><italic>Am J Respir Crit Care Med.</italic></source> (<year>2021</year>) <volume>203</volume>:<fpage>356</fpage>&#x2013;<lpage>65</lpage>. <pub-id pub-id-type="doi">10.1164/rccm.201912-2330OC</pub-id> <pub-id pub-id-type="pmid">32758008</pub-id></citation></ref>
<ref id="B9"><label>9.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Simor</surname> <given-names>P</given-names></name> <name><surname>van der Wijk</surname> <given-names>G</given-names></name> <name><surname>Nobili</surname> <given-names>L</given-names></name> <name><surname>Peigneux</surname> <given-names>P</given-names></name></person-group>. <article-title>The microstructure of REM sleep: why phasic and tonic?</article-title> <source><italic>Sleep Med Rev.</italic></source> (<year>2020</year>) <volume>52</volume>:<issue>101305</issue>. <pub-id pub-id-type="doi">10.1016/j.smrv.2020.101305</pub-id> <pub-id pub-id-type="pmid">32259697</pub-id></citation></ref>
<ref id="B10"><label>10.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Galbiati</surname> <given-names>A</given-names></name> <name><surname>Sforza</surname> <given-names>M</given-names></name> <name><surname>Fasiello</surname> <given-names>E</given-names></name> <name><surname>Casoni</surname> <given-names>F</given-names></name> <name><surname>Marrella</surname> <given-names>N</given-names></name> <name><surname>Leitner</surname> <given-names>C</given-names></name><etal/></person-group> <article-title>The association between emotional dysregulation and REM sleep features in insomnia disorder.</article-title> <source><italic>Brain Cogn.</italic></source> (<year>2020</year>) <volume>146</volume>:<issue>105642</issue>. <pub-id pub-id-type="doi">10.1016/j.bandc.2020.105642</pub-id> <pub-id pub-id-type="pmid">33190030</pub-id></citation></ref>
<ref id="B11"><label>11.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Zhang</surname> <given-names>J</given-names></name> <name><surname>Jin</surname> <given-names>X</given-names></name> <name><surname>Li</surname> <given-names>R</given-names></name> <name><surname>Gao</surname> <given-names>Y</given-names></name> <name><surname>Li</surname> <given-names>J</given-names></name> <name><surname>Wang</surname> <given-names>G</given-names></name></person-group>. <article-title>Influence of rapid eye movement sleep on all-cause mortality: a community-based cohort study.</article-title> <source><italic>Aging (Albany NY).</italic></source> (<year>2019</year>) <volume>11</volume>:<fpage>1580</fpage>&#x2013;<lpage>8</lpage>. <pub-id pub-id-type="doi">10.18632/aging.101858</pub-id> <pub-id pub-id-type="pmid">30867337</pub-id></citation></ref>
<ref id="B12"><label>12.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Leary</surname> <given-names>EB</given-names></name> <name><surname>Watson</surname> <given-names>KT</given-names></name> <name><surname>Ancoli-Israel</surname> <given-names>S</given-names></name> <name><surname>Redline</surname> <given-names>S</given-names></name> <name><surname>Yaffe</surname> <given-names>K</given-names></name> <name><surname>Ravelo</surname> <given-names>LA</given-names></name><etal/></person-group> <article-title>Association of rapid eye movement sleep with mortality in middle-aged and older adults.</article-title> <source><italic>JAMA Neurol.</italic></source> (<year>2020</year>) <volume>77</volume>:<fpage>1</fpage>&#x2013;<lpage>12</lpage>. <pub-id pub-id-type="doi">10.1001/jamaneurol.2020.2108</pub-id> <pub-id pub-id-type="pmid">32628261</pub-id></citation></ref>
<ref id="B13"><label>13.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Matthews</surname> <given-names>KA</given-names></name> <name><surname>Kamarck</surname> <given-names>TW</given-names></name> <name><surname>Hall</surname> <given-names>MH</given-names></name> <name><surname>Strollo</surname> <given-names>PJ</given-names></name> <name><surname>Owens</surname> <given-names>JF</given-names></name> <name><surname>Buysse</surname> <given-names>DJ</given-names></name><etal/></person-group> <article-title>Blood pressure dipping and sleep disturbance in African-American and caucasian men and women.</article-title> <source><italic>Am J Hypertens.</italic></source> (<year>2008</year>) <volume>21</volume>:<fpage>826</fpage>&#x2013;<lpage>31</lpage>. <pub-id pub-id-type="doi">10.1038/ajh.2008.183</pub-id> <pub-id pub-id-type="pmid">18483473</pub-id></citation></ref>
<ref id="B14"><label>14.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Quan</surname> <given-names>SF</given-names></name> <name><surname>Howard</surname> <given-names>BV</given-names></name> <name><surname>Iber</surname> <given-names>C</given-names></name> <name><surname>Kiley</surname> <given-names>JP</given-names></name> <name><surname>Nieto</surname> <given-names>FJ</given-names></name> <name><surname>O&#x2019;Connor</surname> <given-names>GT</given-names></name><etal/></person-group> <article-title>The sleep heart health study: design, rationale, and methods.</article-title> <source><italic>Sleep.</italic></source> (<year>1997</year>) <volume>20</volume>:<fpage>1077</fpage>&#x2013;<lpage>85</lpage>.</citation></ref>
<ref id="B15"><label>15.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Redline</surname> <given-names>S</given-names></name> <name><surname>Sanders</surname> <given-names>MH</given-names></name> <name><surname>Lind</surname> <given-names>BK</given-names></name> <name><surname>Quan</surname> <given-names>SF</given-names></name> <name><surname>Iber</surname> <given-names>C</given-names></name> <name><surname>Gottlieb</surname> <given-names>DJ</given-names></name><etal/></person-group> <article-title>Methods for obtaining and analyzing unattended polysomnography data for a multicenter study. sleep heart health research group.</article-title> <source><italic>Sleep.</italic></source> (<year>1998</year>) <volume>21</volume>:<fpage>759</fpage>&#x2013;<lpage>67</lpage>. <pub-id pub-id-type="doi">10.1093/sleep/21.7.759</pub-id> <pub-id pub-id-type="pmid">11300121</pub-id></citation></ref>
<ref id="B16"><label>16.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Yan</surname> <given-names>B</given-names></name> <name><surname>Wu</surname> <given-names>Y</given-names></name> <name><surname>Fan</surname> <given-names>X</given-names></name> <name><surname>Lu</surname> <given-names>Q</given-names></name> <name><surname>Ma</surname> <given-names>X</given-names></name> <name><surname>Bai</surname> <given-names>L</given-names></name></person-group>. <article-title>Sleep fragmentation and incidence of congestive heart failure: the sleep heart health study.</article-title> <source><italic>J Clin Sleep Med.</italic></source> (<year>2021</year>) <volume>17</volume>:<fpage>1619</fpage>&#x2013;<lpage>25</lpage>. <pub-id pub-id-type="doi">10.5664/jcsm.9270</pub-id> <pub-id pub-id-type="pmid">33779541</pub-id></citation></ref>
<ref id="B17"><label>17.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Punjabi</surname> <given-names>NM</given-names></name> <name><surname>Caffo</surname> <given-names>BS</given-names></name> <name><surname>Goodwin</surname> <given-names>JL</given-names></name> <name><surname>Gottlieb</surname> <given-names>DJ</given-names></name> <name><surname>Newman</surname> <given-names>AB</given-names></name> <name><surname>O&#x2019;Connor</surname> <given-names>GT</given-names></name><etal/></person-group> <article-title>Sleep-disordered breathing and mortality: a prospective cohort study.</article-title> <source><italic>PLoS Med.</italic></source> (<year>2009</year>) <volume>6</volume>:<issue>e1000132</issue>. <pub-id pub-id-type="doi">10.1371/journal.pmed.1000132</pub-id> <pub-id pub-id-type="pmid">19688045</pub-id></citation></ref>
<ref id="B18"><label>18.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Writing Group</surname> <given-names>M</given-names></name> <name><surname>Mozaffarian</surname> <given-names>D</given-names></name> <name><surname>Benjamin</surname> <given-names>EJ</given-names></name> <name><surname>Go</surname> <given-names>AS</given-names></name> <name><surname>Arnett</surname> <given-names>DK</given-names></name> <name><surname>Blaha</surname> <given-names>MJ</given-names></name><etal/></person-group> <article-title>Heart disease and stroke statistics-2016 update: a report from the american heart association.</article-title> <source><italic>Circulation.</italic></source> (<year>2016</year>) <volume>133</volume>:<fpage>e38</fpage>&#x2013;<lpage>360</lpage>.</citation></ref>
<ref id="B19"><label>19.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Lee</surname> <given-names>SWH</given-names></name> <name><surname>Ng</surname> <given-names>KY</given-names></name> <name><surname>Chin</surname> <given-names>WK</given-names></name></person-group>. <article-title>The impact of sleep amount and sleep quality on glycemic control in type 2 diabetes: a systematic review and meta-analysis.</article-title> <source><italic>Sleep Med Rev.</italic></source> (<year>2017</year>) <volume>31</volume>:<fpage>91</fpage>&#x2013;<lpage>101</lpage>. <pub-id pub-id-type="doi">10.1016/j.smrv.2016.02.001</pub-id> <pub-id pub-id-type="pmid">26944909</pub-id></citation></ref>
<ref id="B20"><label>20.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Covassin</surname> <given-names>N</given-names></name> <name><surname>Singh</surname> <given-names>P</given-names></name></person-group>. <article-title>Sleep duration and cardiovascular disease risk: epidemiologic and experimental evidence.</article-title> <source><italic>Sleep Med Clin.</italic></source> (<year>2016</year>) <volume>11</volume>:<fpage>81</fpage>&#x2013;<lpage>9</lpage>. <pub-id pub-id-type="doi">10.1016/j.jsmc.2015.10.007</pub-id> <pub-id pub-id-type="pmid">26972035</pub-id></citation></ref>
<ref id="B21"><label>21.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Blumberg</surname> <given-names>MS</given-names></name> <name><surname>Lesku</surname> <given-names>JA</given-names></name> <name><surname>Libourel</surname> <given-names>PA</given-names></name> <name><surname>Schmidt</surname> <given-names>MH</given-names></name> <name><surname>Rattenborg</surname> <given-names>NC</given-names></name></person-group>. <article-title>What is REM sleep?</article-title> <source><italic>Curr Biol.</italic></source> (<year>2020</year>) <volume>30</volume>:<fpage>R38</fpage>&#x2013;<lpage>49</lpage>.</citation></ref>
<ref id="B22"><label>22.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>McCarley</surname> <given-names>RW</given-names></name></person-group>. <article-title>Neurobiology of REM and NREM sleep.</article-title> <source><italic>Sleep Med.</italic></source> (<year>2007</year>) <volume>8</volume>:<fpage>302</fpage>&#x2013;<lpage>30</lpage>. <pub-id pub-id-type="doi">10.1016/j.sleep.2007.03.005</pub-id> <pub-id pub-id-type="pmid">17468046</pub-id></citation></ref>
<ref id="B23"><label>23.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Smagula</surname> <given-names>S</given-names></name> <name><surname>Reynolds</surname> <given-names>C</given-names></name> <name><surname>Ancoli-Israel</surname> <given-names>S</given-names></name> <name><surname>Barrett-Connor</surname> <given-names>E</given-names></name> <name><surname>Dam</surname> <given-names>TT</given-names></name> <name><surname>Hughes-Austin</surname> <given-names>JM</given-names></name><etal/></person-group> <article-title>Sleep architecture and mental health among community-dwelling older men.</article-title> <source><italic>Journals Gerontol Series B Psychol Sci Soc Sci.</italic></source> (<year>2015</year>) <volume>70</volume>:<fpage>673</fpage>&#x2013;<lpage>81</lpage>. <pub-id pub-id-type="doi">10.1093/geronb/gbt125</pub-id> <pub-id pub-id-type="pmid">24326077</pub-id></citation></ref>
<ref id="B24"><label>24.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Song</surname> <given-names>Y</given-names></name> <name><surname>Blackwell</surname> <given-names>T</given-names></name> <name><surname>Yaffe</surname> <given-names>K</given-names></name> <name><surname>Ancoli-Israel</surname> <given-names>S</given-names></name> <name><surname>Redline</surname> <given-names>S</given-names></name> <name><surname>Stone</surname> <given-names>K</given-names></name></person-group>. <article-title>Relationships between sleep stages and changes in cognitive function in older men: the MrOS sleep study.</article-title> <source><italic>Sleep.</italic></source> (<year>2015</year>) <volume>38</volume>:<fpage>411</fpage>&#x2013;<lpage>21</lpage>. <pub-id pub-id-type="doi">10.5665/sleep.4500</pub-id> <pub-id pub-id-type="pmid">25325465</pub-id></citation></ref>
<ref id="B25"><label>25.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Scullin</surname> <given-names>MK</given-names></name> <name><surname>Gao</surname> <given-names>C</given-names></name> <name><surname>Fillmore</surname> <given-names>P</given-names></name> <name><surname>Roberts</surname> <given-names>RL</given-names></name> <name><surname>Pruett</surname> <given-names>N</given-names></name> <name><surname>Bliwise</surname> <given-names>DL</given-names></name></person-group>. <article-title>Rapid eye movement sleep mediates age-related decline in prospective memory consolidation.</article-title> <source><italic>Sleep.</italic></source> (<year>2019</year>) <volume>42</volume>:<issue>zsz055</issue>. <pub-id pub-id-type="doi">10.1093/sleep/zsz055</pub-id> <pub-id pub-id-type="pmid">30860593</pub-id></citation></ref>
<ref id="B26"><label>26.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Sanders</surname> <given-names>MH</given-names></name> <name><surname>Newman</surname> <given-names>AB</given-names></name> <name><surname>Haggerty</surname> <given-names>CL</given-names></name> <name><surname>Redline</surname> <given-names>S</given-names></name> <name><surname>Lebowitz</surname> <given-names>M</given-names></name> <name><surname>Samet</surname> <given-names>J</given-names></name><etal/></person-group> <article-title>Sleep and sleep-disordered breathing in adults with predominantly mild obstructive airway disease.</article-title> <source><italic>Am J Respir Crit Care Med.</italic></source> (<year>2003</year>) <volume>167</volume>:<fpage>7</fpage>&#x2013;<lpage>14</lpage>. <pub-id pub-id-type="doi">10.1164/rccm.2203046</pub-id> <pub-id pub-id-type="pmid">12502472</pub-id></citation></ref>
<ref id="B27"><label>27.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Gottlieb</surname> <given-names>DJ</given-names></name> <name><surname>Yenokyan</surname> <given-names>G</given-names></name> <name><surname>Newman</surname> <given-names>AB</given-names></name> <name><surname>O&#x2019;Connor</surname> <given-names>GT</given-names></name> <name><surname>Punjabi</surname> <given-names>NM</given-names></name> <name><surname>Quan</surname> <given-names>SF</given-names></name><etal/></person-group> <article-title>Prospective study of obstructive sleep apnea and incident coronary heart disease and heart failure: the sleep heart health study.</article-title> <source><italic>Circulation.</italic></source> (<year>2010</year>) <volume>122</volume>:<fpage>352</fpage>&#x2013;<lpage>60</lpage>. <pub-id pub-id-type="doi">10.1161/circulationaha.109.901801</pub-id> <pub-id pub-id-type="pmid">20625114</pub-id></citation></ref>
<ref id="B28"><label>28.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Azarbarzin</surname> <given-names>A</given-names></name> <name><surname>Sands</surname> <given-names>SA</given-names></name> <name><surname>Taranto-Montemurro</surname> <given-names>L</given-names></name> <name><surname>Vena</surname> <given-names>D</given-names></name> <name><surname>Sofer</surname> <given-names>T</given-names></name> <name><surname>Kim</surname> <given-names>SW</given-names></name><etal/></person-group> <article-title>The sleep Apnea-specific hypoxic burden predicts incident heart failure.</article-title> <source><italic>Chest.</italic></source> (<year>2020</year>) <volume>158</volume>:<fpage>739</fpage>&#x2013;<lpage>50</lpage>. <pub-id pub-id-type="doi">10.1016/j.chest.2020.03.053</pub-id> <pub-id pub-id-type="pmid">32298733</pub-id></citation></ref>
<ref id="B29"><label>29.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Fraigne</surname> <given-names>JJ</given-names></name> <name><surname>Grace</surname> <given-names>KP</given-names></name> <name><surname>Horner</surname> <given-names>RL</given-names></name> <name><surname>Peever</surname> <given-names>J</given-names></name></person-group>. <article-title>Mechanisms of REM sleep in health and disease.</article-title> <source><italic>Curr Opin Pulm Med.</italic></source> (<year>2014</year>) <volume>20</volume>:<fpage>527</fpage>&#x2013;<lpage>32</lpage>. <pub-id pub-id-type="doi">10.1097/mcp.0000000000000103</pub-id> <pub-id pub-id-type="pmid">25221856</pub-id></citation></ref>
<ref id="B30"><label>30.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Gonnissen</surname> <given-names>HK</given-names></name> <name><surname>Mazuy</surname> <given-names>C</given-names></name> <name><surname>Rutters</surname> <given-names>F</given-names></name> <name><surname>Martens</surname> <given-names>EA</given-names></name> <name><surname>Adam</surname> <given-names>TC</given-names></name> <name><surname>Westerterp-Plantenga</surname> <given-names>MS</given-names></name></person-group>. <article-title>Sleep architecture when sleeping at an unusual circadian time and associations with insulin sensitivity.</article-title> <source><italic>PLoS One.</italic></source> (<year>2013</year>) <volume>8</volume>:<issue>e72877</issue>. <pub-id pub-id-type="doi">10.1371/journal.pone.0072877</pub-id> <pub-id pub-id-type="pmid">23951335</pub-id></citation></ref>
<ref id="B31"><label>31.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Van Cauter</surname> <given-names>E</given-names></name> <name><surname>Leproult</surname> <given-names>R</given-names></name> <name><surname>Plat</surname> <given-names>L</given-names></name></person-group>. <article-title>Age-related changes in slow wave sleep and REM sleep and relationship with growth hormone and cortisol levels in healthy men.</article-title> <source><italic>Jama.</italic></source> (<year>2000</year>) <volume>284</volume>:<fpage>861</fpage>&#x2013;<lpage>8</lpage>. <pub-id pub-id-type="doi">10.1001/jama.284.7.861</pub-id> <pub-id pub-id-type="pmid">10938176</pub-id></citation></ref>
</ref-list>
<glossary>
<title>Abbreviations</title>
<def-list id="DL1">
<def-item><term>AHI</term><def><p>apnea&#x2013;hypopnea index</p></def></def-item>
<def-item><term>BMI</term><def><p>body mass index</p></def></def-item>
<def-item><term>HF</term><def><p>heart failure</p></def></def-item>
<def-item><term>CI</term><def><p>confidence interval</p></def></def-item>
<def-item><term>CVD</term><def><p>cardiovascular disease</p></def></def-item>
<def-item><term>HDL</term><def><p>high-density lipoprotein</p></def></def-item>
<def-item><term>HR</term><def><p>hazard ratio</p></def></def-item>
<def-item><term>MI</term><def><p>myocardial infarction</p></def></def-item>
<def-item><term>MrOS</term><def><p>Outcomes of Sleep Disorders in Older Men</p></def></def-item>
<def-item><term>PSG</term><def><p>polysomnography</p></def></def-item>
<def-item><term>REM</term><def><p>rapid eye movement</p></def></def-item>
<def-item><term>SHHS</term><def><p>Sleep Heart Health Study</p></def></def-item>
<def-item><term>T90</term><def><p>percent time below oxygen desaturation 90%.</p></def></def-item>
</def-list>
</glossary>
</back>
</article>