As the most consumed drink in the world, coffee is second only to water (Butt and Sultan, 2011). In European countries, most adults drink coffee every day (Lopez Garcia et al., 2014). Evidence has been found in recent years that coffee has benefit to the health. People who drink three or four cups of coffee a day have a lower risk of developing type 2 diabetes, which may be due to the presence of green folic acid and caffeine in coffee (George et al., 2008). Moreover, a large amount research reveals that caffeine in the coffee with moderate consumption (three-to-five cups, volume not identified) has the effect of anti-Alzheimer’s disease (Mahshad and Mazen, 2017). Caffeine and coffee with a dose of 600 ml/day are helpful to reduce the risk of depression (Grosso et al., 2016). It is said that caffeine and modafinil could improve neuroinflammation and anxiety during sleep deprivation in rats by inhibiting microglial activation (Meetu et al., 2018), while an excessive dose of caffeine (70 mg/kg) showed anxiogenic effect (Kayir and Uzbay, 2006). Drinking coffee also can enhance cognitive function, in which it is believed that coffee has the benefit for attention and can eliminate cognitive sequelae caused by poor sleep (Franke et al., 2014). However, excessive intake of coffee or caffeine can lead to the development of physiological tolerance, and when a habitual caffeine consumer suddenly reduces or ceases taking caffeine, he or she may experience withdrawal symptoms (Hughes et al., 1998; Stachyshyn et al., 2021).

Coffee contains more than 1,000 different compounds including phenolics, diterpenes, and melanoidins (Renouf et al., 2014), of which about 1% is caffeine (Hoelzl et al., 2010; Kim et al., 2017). Studies have proven that caffeine can improve attention measurement and alertness (Haskell et al., 2005; Childs and Wit, 2006). However, excessive caffeine intake can lead to negative health consequences, such as psychomotor agitation, insomnia, headaches, and gastrointestinal discomfort (Wierzejska, 2012). Caffeine and its metabolites pass freely across the placenta into a fetus. Studies have shown that it may bring damage to the fetus by affecting the expression of genes related to cell damage (Abdelkader et al., 2013). Some recent systematic reviews have shown that moderate intake (three cups a day) of various types of coffee can reduce all-cause mortality in healthy people. These benefits may be due to some biologically active compounds instead of caffeine, mainly phenolic acids and diterpenoids, like cafestol and kahweol (Ding et al., 2015; Tsujimoto et al., 2017; Li et al., 2019). Thus, decaffeinated coffee appeared on the market. Decaffeinated coffee contains only a small amount of caffeine, and the International Coffee Organization defines that the content of caffeine is less than 0.3% in decaffeinated coffee. Chlorogenic acid, a kind of phenolic phytochemicals, can represent the principal non-caffeine components in coffee. Decaffeinated coffee with high chlorogenic acid content improves alertness and reduces negative emotions (Camfield et al., 2013). However, these effects of using chlorogenic acid alone are not obvious, considering that it may be the synergistic effect of non-caffeine compounds in coffee (Camfield et al., 2013). To study the effects of coffee on humans, Bunker and McWilliams proposed a criteria in 1979 to define decaffeinated coffee and coffee, using commercial-branded coffee and espresso (caffeine-containing coffee and caffeine-containing coffee 5 mg per cup) (Adan et al., 2008). Studying the impact of coffee or decaffeinated coffee on cognition can better understand daily habits in life and further clarify the benefits of coffee or decaffeinated coffee (Ho and Chung, 2013).

Sleep deprivation has become a health problem in the modern society (Malinalli et al., 2018). Sleep deprivation can be acute or chronic (Jamie et al., 2019). By definition, 24 h without sleep is acute sleep loss, and less than 6 h of sleep per night for 6 nights or more in a row is considered chronic sleep deprivation (Krishnan et al., 2016). The consequences of sleep deprivation are enormous, especially in mental illness (World Health Organization, 2017). Evidence suggests that rapid eye movement sleep changes occur in most patients with mental illness, such as depression (Benca et al., 1992). Furthermore, sleep deprivation may also occur in the same symptoms (Dieter et al., 2019). A study found that the cytokine secretion induced by low-level exposure of immune cells to bacterial cell wall components contributes to normal sleep patterns, while excessive cytokine levels are associated with disrupted sleep (Galland, 2014). At the same time, recent investigations indicated that the alteration of gut microbiome patterns was evident in people with depression (Barandouzi et al., 2020).

Our previous study found that chronic paradoxical sleep deprivation (PSD) could lead to depression-like behaviors, as well as dysbiosis in the host’s gut microbiota (Ma et al., 2019). PSD could alter monoamine neurotransmitters such as norepinephrine and serotonin, as well as increase neuro-inflammatory cytokines including IL-1β and TNF-α, microglial activation, and neuronal apoptosis in the brain (Daniele et al., 2017; Mengmei et al., 2017). Sleep deprivation also leads to an accumulation of reactive oxygen species and oxidative stress, specifically in the gut (Alexandra et al., 2020). In addition, some preclinical studies have shown that gut microbiota can affect behaviors and brain conditions through neuroimmunity, neuroendocrine, neural, and humoral pathways (Dinan and Cryan, 2013; Kelly et al., 2016). Coffee has been proven to regulate the gut microbiota (González et al., 2020), which depends more on polyphenols and other non-digestible constituents of coffee like polysaccharides and melanoidins (Kolb et al., 2020). Coffee is the most common beverage used to combat fatigue and fatigue caused by sleep deprivation, while decaffeinated coffee is considered as a healthier alternative to traditional coffee. For the purpose of better understanding the effects of these two beverages on sleep deprivation, we first observed the intervention effect of coffee and decaffeinated coffee on the PSD rat model induced by multi-platform technology, mainly related to depression-related behavioral changes and serum inflammation and oxidative stress indicators. Then, we investigated their impacts on the corresponding alterations in the gut microbiota.

Chronic sleep deprivation is a stressor that impairs the brain function and causes cognitive impairment, as well as increases oxidative stress and the risk for Alzheimer’s disease or depression (McEwen, 2006; Ma et al., 2019). The results of the behavior tests in our study showed the similar depression-like behaviors after PSD induced, and the symptom could be improved in a different extent with the treatment of conventional coffee and decaffeinated coffee (Figure 1). It has been reported that caffeinated coffee and caffeine were beneficial to depression-like behaviors, while the effect of decaffeinated coffee was not obvious (Paz-Graniel et al., 2020; Xue et al., 2020).

Elevated levels of IL-6 and TNF-α, as well as a negative feedback of SOD and GSH-Px levels in the PSD group (Table 1) confirmed that sleep deprivation induced inflammation and oxidative stress. Both IL-6 and TNF-α are the multifunctional cytokines involved in the regulation of the immune response and inflammation, and the production of these pro-inflammatory cytokines could be increased by different stimuli (Akira et al., 1990; Schindler et al., 1990). As one of the stimuli, sleep disturbance was associated with disorders related to inflammation, such as cardiovascular disease, arthritis, diabetes mellitus, and certain cancers (Michael et al., 2015). In addition, evidence suggested that sleep deprivation would promote oxidative stress (Villafuerte et al., 2016). In our study, the levels of IL-6, TNF-α, SOD, and GSH-Px were all reversed after the treatment of conventional coffee and decaffeinated coffee, while the effect of coffee was relatively more significant than that of decaffeinated coffee (Table 1). The anti-inflammatory effect of coffee has been widely reported (Yamashita et al., 2012; Erikka et al., 2015). In our study, both in the caffeinated coffee group and the decaffeinated coffee group, a decrease in the levels of pro-inflammatory factors was observed, and the therapeutic effect of caffeinated coffee was more obvious, which indicated that not only caffeine but also the other ingredients in coffee played a role in promoting anti-inflammatory effect, such as chlorogenic acid (Dong et al., 2019). Chlorogenic acid can inhibit protein tyrosine phosphatase 1B to reduce the expression of pro-inflammatory cytokine genes (Giuseppe et al., 2017). Research on the effect of coffee and its biologically active substances such as caffeine, phenolic compounds, diterpenoids. and soluble fiber on oxidative stress is increasing these years (Martini et al., 2016). It has been reported that chronic coffee and caffeine ingestion would increase the activity of SOD, as well as protect the antioxidant system in the brain (Abreu et al., 2011). Light-dark roasted coffee (rich in chlorogenic acid) showed a more significant effect in increasing the level of SOD (Kotyczka et al., 2011). Evidence showed that some diterpenoids (kafestol and kahweol) in coffee could increase the concentration of GSH (Scharf et al., 2001). Furthermore, caffeine also has the exact effect of antioxidant and anti-inflammatory (Daniela et al., 2017; Soohan et al., 2017; Haroon et al., 2019).

Coffee has been confirmed to confer various health benefits, and drinking coffee can alter a host’s gut microbiota (Chong et al., 2020). Coffee may partly depend on the modulation of gut microbiota to influence health (González et al., 2020). It has been proven that polyphenols in coffee can change the environment, or they can be catabolized by gut microbiota (Aura, 2008; Couteau et al., 2010). In the microbial community profiling, both caffeinated coffee and decaffeinated coffee could reduce the number of OTUs that increased after PSD induction. Only the Simpson index and Shannon index in alpha diversity index were restored significantly after coffee treatment. In the beta diversity analysis, there was a significant separation between the control group and the model group. With the treatment of coffee and decaffeinated coffee, the composition of the gut microbiota tended to approach the control group, which indicated that both coffee and decaffeinated coffee restored the composition of the gut microbiota of PSD rats. In our results, the levels of Akkermansia (Phylum Verrucomicrobia) and Klebsiella (Phylum Proteobacteria) were significantly decreased in the rats with sleep deprivation (Figure 6B). As a Gram-negative pathogen, Klebsiella could cause a variety of infectious diseases (Guoying et al., 2020) and has the effect of inducing the inflammatory response (Atarashi et al., 2017; Marjolaine et al., 2019). It has been reported that when the Proteobacteria increases, intestinal mucus would decrease, resulting in damage to the intestinal barrier and low-grade inflammation (Shin et al., 2015). In our results, sleep deprivation caused an increase in the expression of inflammatory factors, while a decrease in the pro-inflammatory bacteria Proteobacteria. This indicated that the inflammation caused by sleep deprivation might be not through the gut microbiota pathway. The decrease of Akkermansia is commonly observed in the symptom of sleep deprivation (Heintz-Buschart et al., 2018; Ting et al., 2019). Akkermansia is known as a beneficial microbe that is inversely associated with obesity, diabetes, cardiometabolic diseases, and low-grade inflammation (Plovier et al., 2016; Patrice and Willem, 2017). With treatment of conventional coffee and decaffeinated coffee, both levels of Akkermansia were increased significantly, and the effect of coffee was more obvious (Figure 6B). A study has found that coffee has antibacterial effects and prebiotic function (Nakayama and Oishi, 2013). Compared to caffeine, which is rapidly absorbed and degraded in the upper digestive tract, polyphenols are difficult to be absorbed in the gastrointestinal tract. This caused most of the polyphenols to enter the intestine and affect the gut microbiota and mucosal cells and increase of the abundance of Akkermansia in the intestine (Yuji et al., 2018). A study has shown that tea is rich in polyphenols and caffeine plays a key role in remodeling the disturbed gut microbiota (including Akkermansia), which may be a synergistic effect (Xiaoyu et al., 2018).

Our results illustrated that the abundance of Parabacteroides (Phylum Bacteroidetes) in the PSD group was significantly higher than the normal control. As a kind of Gram-negative bacteria, Parabacteroides contains lipopolysaccharide, which is a typical potent endotoxin that can induce strong pro-inflammatory reactions in the host (Kaisa et al., 2020). Akkermansia and Klebsiella, also Gram-negative bacteria, had lower levels in the PSD group, compared to the normal control, and high levels of inflammatory factors were detected after PSD intervention. These indicated that the inflammatory response might not necessarily be caused by Parabacteroides, Akkermansia, and Klebsiella, but rather be caused by the release of lipopolysaccharide from other types of Gram-negative bacteria or other stress response in the host. In addition, a high level of Parabacteroides can be found in patients with depression (Barandouzi et al., 2020), and our results also showed depression-like behaviors after PSD induced. With the treatment of decaffeinated coffee, the decrease of the level of Parabacteroides was relatively more significant than the conventional coffee group. Polyphenols in the decaffeinated green tea and black tea could regulate the abundance of Parabacteroides and induced weight loss (Rothenberg et al., 2018). For example, chlorogenic acid can protect intestinal integrity and reduce inflammation by inhibiting the growth of Bacteroides and the accumulation of Bacteroides-derived lipopolysaccharide (Yan et al., 2020). In addition, evidence has indicated that both caffeinated and decaffeinated coffee have a similar anti-inflammatory effect (Dong et al., 2019), and not only caffeine, but also some phenols including pyrocatechol, chlorogenic acid, and so on, can prevent the inflammatory responses (Hwang et al., 2016; Stefanello et al., 2018; Megumi et al., 2020). Therefore, caffeine and phenols exert anti-inflammatory effects by affecting different gut microbiota.

In our study, the relative abundance of Lachnospiraceae (Phylum Firmicutes), S24-7 (Phylum Bacteroidetes), and Oscillospira (Phylum Firmicutes) were significantly increased in the SD group (Figure 6B). Lachnospiraceae and S24-7 impact their hosts by producing short-chain fatty acids (SCFAs) (Jennifer et al., 2017; Matthew et al., 2020). In patients with ulcerative coliti, an increase in the level of Lachnospiraceae could be observed (Schirmer et al., 2019), which could be explained by the fact that stress increases the abundance of Lachnospiraceae (Li et al., 2017). As shown in our study, after the stress of sleep deprivation, the level of Lachnospiraceae increased significantly. However, as a butyric acid-producing bacteria, increasing the content of Lachnospiraceae also has a beneficial effect to the body (Huws et al., 2011; Dong et al., 2020). Oscillospira can be seen in the obese animals, which ferments polysaccharide into SCFAs (Na et al., 2018). In addition, Oscillospira is correlated with inflammatory disease (Uri et al., 2017). SCFAs are involved in the regulation of the gut immune system, and the production of the SCFAs is one of the crucial ways that gut microbiota affect the hosts (Jost et al., 2020). Besides, SCFAs play an important role in host defense and immunity, including anti-inflammation and anti-oxidant activities. The increase of these gut microbiota related to fatty acid metabolism indicated that sleep deprivation would lead to metabolism disorders, inflammation, and oxidative stress. After the administration of conventional coffee and decaffeinated coffee, the relative abundance of these gut bacteria decreased in different degrees, and coffee had a relatively more significant effect. Caffeine consumption could attenuate the increase in Firmicutes-to-Bacteroidetes ratio in high-fat-fed rats (Cowan et al., 2014). Interestingly, some recent studies have now shown that the increase in this ratio has no relation with the presence of high- fat diet but only related to the content of dietary fiber (Dalby et al., 2017; Singh et al., 2020). Moreover, due to lifestyle-associated factors such as diet, physical activity, food additives, and contaminants, the relative abundance of the Firmicutes and Bacteroidetes varies greatly among individuals (Magne et al., 2020). Caffeine intake is linked to weight loss and the regulation of lipid metabolism, partly through its inhibition of adipogenesis-related factors (Su et al., 2013). It has been reported that some phenols and caffeine were directly associated with Bacteroides group levels (González et al., 2020). A study has found that caffeine and chlorogenic acid in coffee have a partially positive effect to the SCFAs in plasma (Kazuchika et al., 2018). The reaction of polyphenols in tea with residual carbohydrates and gut microbiota within the colon produce SCFAs, which enhance lipid metabolism (Rothenberg et al., 2018).

As shown in the previous studies, the differential gut microbiota in our study is commonly seen in patients with depression (Zheng et al., 2016; Cheung et al., 2019). Gut microbiota influences the emotional behavior by affecting the interactions of the gut–brain axis (Emeran et al., 2015), and sleep deprivation would increase the risk of depression (Robert and Hao, 2014). Chronic PSD could bring about depression-like performance, which is proven by our study and previous researches (Ma et al., 2019; Rahmani et al., 2020). In the behavior tests of our study, the effect of coffee to improve depression is more significant than the decaffeinated coffee. The main difference between the two drinks is the caffeine content. Caffeine is an alkaloid and modulates the dopaminergic activity through nonspecific antagonism against A1/A2 adenosine receptors (Navarro et al., 2018). A moderate intake of caffeine has a stimulating effect on the central nervous system and can improve psychomotor activities (Adan et al., 2008). Furthermore, coffee contains many functional components other than caffeine, such as chlorogenic acid, ferulic acid, nicotinic acid, trigonelline, quinolinic acid, tannic acid, and pyrogallic acid. These compounds have anti-inflammatory or antioxidative effects. Chlorogenic acid and trigonelline, which are present in high amounts in coffee, have an anti-inflammatory effect (Godos et al., 2014), and it has been found that low-grade inflammation seems to be related to the pathogenesis of depression (Sanchez Villegas and Martínez González, 2013). From our results of the treatment with decaffeinated coffee, we know that polyphenols in coffee also can improve depression-like behaviors by affecting the gut microbiota associated with inflammation such as Akkermansia, Klebsiella, and Parabacteroides. On the other hand, it has been suggested that patients with depression have increased oxidative stress and decreased antioxidant defense (Black et al., 2015) and antioxidant is an important aspect of treating depression (Vaváková et al., 2015). Coffee is rich in polyphenols, which not only has an anti-inflammatory effect but also has antioxidant activity (Godos et al., 2014; Martini et al., 2016). In our study, the abundance of the gut microbiota related to oxidative stress such as S24-7, Lachnospiraceae, and Oscillospira, could be revised by both coffee and decaffeinated coffee. Thus, it is demonstrated that the anti-inflammatory and antioxidant effects of polyphenols may be through regulating the gut microbiota, further playing a role in the treatment of depression induced by chronic PSD.

Some limitations must be considered when interpreting our results. The manufacturing procedure of the instant coffee powder we used in the experiment involves the aqueous extraction of soluble coffee components followed by drying to form a soluble powder. Although there are no other food additives, the loss of volatile aroma compounds during concentration through evaporation will lower product quality (Beverly et al., 2020), and at the same time, the results of the study could not fully represent the activity of coffee. In addition, the study lacks the analysis of the components of the samples, although there are other relevant literatures for reference, as well as the analysis of the metabolites of gut microbiota (such as SCFAs), these need to be strengthened in future research to better judge the role of gut microbiota in coffee on sleep deprivation.

In this study, 16S rRNA gene sequencing was applied to assess the effects of conventional coffee and decaffeinated coffee on the gut microbial community profiling. Our results revealed that the administration of conventional coffee and decaffeinated coffee ameliorated depression-like behaviors in rats of PSD induced, as well as the changed levels of IL-6, TNF-α, SOD, and GSH-Px. The effect of conventional coffee was relatively obvious than that of decaffeinated coffee. In microbiome analysis, PSD disturbed the composition of gut microbiota, including Akkermansia, S24-7, Lachnospiraceae, Oscillospira, Parabacteroides, and Klebsiella. Both the treatment of conventional coffee and decaffeinated coffee could restore the abundance levels of these gut microbiota. In a word, both coffee and decaffeinated coffee are effective for sleep deprivation-induced depression-like behaviors and the dysbiosis of gut microbiota. It implies that caffeine is not the only key substance of coffee in the regulation of PSD induced gut microbiota disorder.

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: https://www.ncbi.nlm.nih.gov/, PRJNA762663.

The animal study was reviewed and approved by Animal Experiment Center, Shanghai University of Traditional Chinese Medicine.

YX, TZ, MZ, CX, and LY accomplished the conception and design of the research. XG, SZ, WM, QW, and YL performed the experiments. XG and SZ prepared the figures. XG, WM, and SZ analyzed and interpreted the data. XG, WM, and YL drafted the manuscript. MZ edited and revised the manuscript. MZ and LY approved final version of the manuscript. All authors read and approved the final manuscript.

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.

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.