Three S (3S)—Seiri (Sort in English), Seiton (Set in English), and Seiso (Shine in English)—are reported to have been practiced in Japanese companies since the 1800s (1). “Seiri” means classifying things into necessary and unnecessary items and removing the unnecessary ones. “Seiton” means organizing necessary items so that they can be easily accessed. “Seiso” means to sweep and tidy up. Adding “Seiketsu (Standardize in English)” and “Shitsuke (Sustain in English)” to this, it is sometimes called Five S (5S). These practices have helped companies overcome various problems such as lack of workers discipline and diligence, waste reduction and savings during economic downturns, workplace safety, and productivity improvement.

Although 3S is an activity that originated in Japan, it is now used as a quality management tool in manufacturing and healthcare services in other countries (2). Many companies widely implement 3S behaviors, often as part of occupational health and safety initiatives. It is recommended to work on organizing and setting things in order as part of the prevention of accidents involving falls. In addition, 3S is included in workplace mental health action checklists aimed at improving the work environment, and is expected to have positive psychological effects on workers (3).

Such psychological effects are often assessed using both negative and positive indicators, with psychological distress and work engagement being commonly used indicators. Psychological distress is commonly defined as a state of emotional suffering characterized by symptoms of depression and anxiety, often accompanied by somatic complaints such as insomnia or fatigue. It is widely conceptualized as a continuum of symptom severity rather than a discrete diagnostic category (4). In contrast, work engagement is generally understood as a positive, fulfilling work-related state of mind that is characterized by vigor, dedication, and absorption. Vigor reflects high levels of energy and resilience at work, dedication denotes strong involvement and a sense of enthusiasm and significance, and absorption describes being fully concentrated and happily engrossed in work (5).

3S behaviors, based on the Job Demands-Resources (JD-R) Model, have the potential to reduce psychological distress and increase work engagement. The JD-R model, a widely used framework of occupational stress research, outlines two primary processes (6, 7). The first is the motivational process, in which job resources—defined as physical, psychological, social, or organizational aspects of the job that help achieve work goals, reduce job demands and their associated costs, or promote personal growth and development—enhance motivation, including work engagement. The second is the health-impairment process, in which job demands—defined as aspects of the job that require sustained physical or mental effort and are therefore associated with certain physiological and psychological costs—lead to strain, such as psychological distress. Job resources play a critical role in buffering the negative effects of job demands, thereby contributing to employees’ health and performance. When the 3S of work are in good condition, it is believed that employees have a clearer understanding of what tasks need to be done and how to perform them. Such a work environment with good 3S conditions can itself serve as a job resource. Specifically, 3S improves role clarity, reduces unnecessary effort, and enhances efficiency. In this way, good 3S conditions are expected to lower perceived job demands and simplify work processes, thereby decreasing workload and the likelihood of errors. As a result, good 3S status may be associated with lower psychological distress. Moreover, since job resources are positively associated with work engagement, good 3S conditions may also contribute to higher work engagement.

Previous research suggests that a cluttered environment can reduce feelings of fulfillment, happiness and the sense of safety and security derived from being in one’s personal space (8). 3S behaviors improve a cluttered environment, which in turn may increase feelings of safety and security. In addition, the psychological effects of tidy-up behavior on university students reported positive effects on wellbeing (9). However, there are no studies that have identified the relationship between 3S behaviors and negative mental health status such as psychological distress, or positive work-related psychology such as work engagement. This study aims to clarify the relationship between 3S behaviors status, psychological distress, and work engagement in the workplace.

Among 9,451 participants, a total of 6,156 individuals participated in the follow-up survey (response rate was 65%). The characteristics of the study participants are shown in Table 1. The workers with 3S behaviors were 3,862 (62.7%), without 3S behaviors were 1,848 (30.0%) and unknown workers were 446 (7.2%). The mean age (standard deviation [SD]) of each 3S behaviors status (“with 3S behaviors,” “without 3S behaviors,” “unknown”) were 48.2 (SD: 13.1), 47.7 (SD: 12.9), and 45.1 (SD: 13.4), respectively. The K6 scores at follow-up were 4.6 (5.0), 5.4 (5.5), and 5.9 (5.7), while the UWES-9 scores at follow-up were 2.6 (1.2), 2.3 (1.1), and 2.2 (1.1), respectively.

Table 2 shows the number and proportion of workers implementing 3S behaviors. While 67% of female workers habitually performed 3S behaviors, only 59% of male workers did so. The implementation rate of 3S behavior increased with age. Compared to manufacturing (67%) and construction (69%), implementation rates were low in primary industries and information and communications (47%), while high in accommodations, eating and drinking services (77%) and medical, health care and welfare (73%).

Table 3 shows the relationship between 3S behaviors and psychological distress/work engagement at follow-up. After adjusting for industry type (Model 1), psychological distress of workers without 3S behaviors was higher compared to workers with 3S behaviors (standerdized coefficient = 0.03, p = 0.006). In Model 2 (further included baseline K6 scores as covariates), psychological distress of workers without 3S behaviors was higher (standerdized coefficient = 0.03, p = 0.006).

Work engagement of workers without 3S behaviors was lower compared to workers with 3S behaviors in Model 1 (standerdized coefficient = −0.10, p < 0.001). In Model 2 (further included baseline UWES-9 scores as covariates), there was no statistically significant relationship between 3S behaviors and work engagement (standerdized coefficient = −0.01, p = 0.339).

The results of the additional analysis that included “unknown” as either “no” or “yes” for the 3S behavior are shown in Supplementary Tables 1, 2. The group of workers without 3S behavior/unknown had significantly higher K6 values compared to the group of workers with 3S behavior (Supplementary Table 1). The group of workers without 3S behavior also showed a similar trend toward higher K6 values compared to the group of workers with 3S behavior/unknown (Supplementary Table 2). WE did not show statistically significant differences, while consistent with the results of the main analysis.

Workers who practiced 3S behaviors had significantly lower psychological distress than those who reported not practicing in 3S behaviors. There was no statistically significant relationship between 3S behavior and work engagement.

In this study, working in a cluttered environment was suggested to induce feelings of depression and anxiety. It has been shown that when people set goals and work on something, they retrieve the information they need from what they have in their field of vision (14). In a disorganized and cluttered environment, they are likely to spend more effort looking for the information they need (15). This may lead to the individual perceiving their workload as high. Based on the JD-R model, it is considered that depression and anxiety (assessed by K6) increased as a stress response. Additionally, a previous study examining the psychological effects of tidy-up behavior of university students reported positive effects on wellbeing from tidy-up behavior (9). An organized and neatened environment may reduce the amount of effort required to obtain the necessary information for a goal, and also reduce discomfort with a cluttered environment due to tidiness.

3S behaviors and work engagement were not related. According to the JD-R model (7, 8), work engagement is associated with work and personal resources. In the analysis without adjusting for work engagement at the baseline survey, there was a relationship between 3S behaviors and work engagement. This analysis suggests that individuals with high work engagement may be more likely to engage in 3S behaviors habitually. This is likely based on the fact that no significant relationship was found between 3S behaviors and work engagement at the follow-up survey after adjusting for work engagement at the baseline survey. There may be no effect of 3S behaviors on increasing work engagement. This point requires further clarification through intervention studies.

Companies have addressed organizational challenges such as fostering discipline, diligence, promoting savings, and ensuring safety through 3S. In addition, the Mental Health Action Checklist for improving the workplace environment, published by the Ministry of Health, Labour and Welfare, has a 30-item action framework, including an organizing item on “making each individual’s work area easier to work in Ministry of Internal Affairs and Communications (16).” The study suggests that the 3S may reduce depression and anxiety among workers. This finding indicates that 3S behaviors are related with lower psychological distress, suggesting that in the workplace, it is expected to promote initiatives within companies not only as a tool for quality management but also as one of the efforts aimed at improving workers’ mental health.

In this study, we have not been able to examine the motivations behind the participants’ 3S behaviors, specifically whether these behaviors were voluntary or based on workplace rules. If the results of this survey indicate effects due to spontaneous behavior, it is possible that some elements of the 3S behaviors influence mental health. Conversely, if the behaviors are based on workplace rules, there may be factors influencing mental health not only related to the 3S behaviors themselves but also to the context in which these behaviors occur. We believe it is necessary to confirm this in future research.

The implementation rate of the 3S behaviors varies depending on attributes, which should be taken into consideration when intervening in the workplace. In this study, the implementation rate of 3S behaviors was low among men and younger individuals. This suggests that daily lifestyle habits are related to the implementation of 3S behaviors. Additionally, this study revealed that there are variations in implementation rates depending on industry. This suggests that workplace initiatives influence 3S behaviors. In accommodation and food services, implementing 3S is considered an essential task and is therefore incorporated into daily operations. In construction, manufacturing, and medical and welfare services, 3S behaviors are often considered essential habits for performing daily tasks without mistakes, and are carried out as activities that everyone in the workplace participates in Anggarini (17). On the other hand, 3S behaviors are not progressing in the information and communications industry. The reason for this may be that the industry mainly involves computer work, and even if 3S is not thoroughly implemented for files stored inside computers, it is unlikely to be noticed by others. In summary, both private life and personal characteristics, as well as workplace initiatives, influence 3S behaviors.

This study has several limitations. First, the questions regarding the presence or absence of 3S behaviors have not been confirmed for validity and reliability. In Japan, children are exposed to the term “3S” from elementary school. There is a daily habit of all students and teachers working together on the 3S in the classroom after lunch break. Therefore, rather than breaking down each behaviors of the 3S, we asked about 3S behavior as a series of actions. However, there may have been people who did not recognize what the 3S behaviors were. In response to the question, “Do you practice the 3S every day?,” 446 (7.2%) participants answered “unknown.” This is likely because the definition of “3S” in the question was ambiguous. We conducted an additional analysis (sensitivity analysis) to see how the results would differ when people who answered “unknown” were allocated to the group that performed 3S behaviors and the group that did not. The results did not differ significantly from the main results (Supplementary Tables 1, 2). It is necessary to consider methods for identifying 3S behaviors in the future. Second, this study only covers workers who are registered with an internet survey company. There is a possibility that people who do not normally use the internet are not included, which limits the generalizability of this study.

Companies have historically addressed various challenges through 3S practices. The results of this study suggest that workers who practice 3S behaviors in the workplace experience lower levels of psychological distress. Sharing these findings with both workers and managerial staff may help to reaffirm the importance of 3S practices in the workplace. Since this study cannot clarify the mechanism by which 3S behavior is associated with low psychological distress, further research is needed to elucidate the mechanism.