Assessment of Stress and Well-Being of Japanese EmployeesUsing Wearable Devices for Sleep Monitoring Combined With Ecological Momentary Assessment Pilot Observational Study

Background: Poor sleep quality can elevate stress levels and diminish overall well-being. Japanese individuals often experiencesleep deprivation, and workers have high levels of stress. Nevertheless, research examining the connection between objectivesleep assessments and stress levels, as well as overall well-being, among Japanese workers is lacking. Objective: This study aims to investigate the correlation between physiological data, including sleep duration and heart ratevariability (HRV), objectively measured through wearable devices, and 3 states (sleepiness, mood, and energy) assessed throughecological momentary assessment (EMA) and use of rating scales for stress and well-being. Methods: A total of 40 office workers (female, 20/40, 50%; mean age 40.4 years, SD 11.8 years) participated in the study.Participants were asked to wear a wearable wristband device for 8 consecutive weeks. EMA regarding sleepiness, mood, andenergy levels was conducted via email messages sent by participants 4 times daily, with each session spaced 3 hours apart. Thisassessment occurred on 8 designated days within the 8-week timeframe. Participants'stress levels and perception of well-beingwere assessed using respective self-rating questionnaires. Subsequently, participants were categorized into quartiles based ontheir stress and well-being scores, and the sleep patterns and HRV indices recorded by the Fitbit Inspire 2 were compared amongthese groups. The Mann-Whitney Utest was used to assess differences between the quartiles, with adjustments made for multiplecomparisons using the Bonferroni correction. Furthermore, EMA results and the sleep and HRV indices were subjected tomultilevel analysis for a comprehensive evaluation Results: The EMA achieved a total response rate of 87.3%, while the Fitbit Inspire 2 wear rate reached 88.0%. When participantswere grouped based on quartiles of well-being and stress-related scores, significant differences emerged. Specifically, individualsin the lowest stress quartile or highest subjective satisfaction quartile retired to bed earlier (P<.001 and P=.01, respectively),whereas those in the highest stress quartile exhibited greater variation in the midpoint of sleep (P<.001). A multilevel analysisunveiled notable relationships: intraindividual variability analysis indicated that higher energy levels were associated with lowerdeviation of heart rate during sleep on the preceding day (beta=-.12, P<.001), and decreased sleepiness was observed on daysfollowing longer sleep durations (beta=-.10, P<.001). Furthermore, interindividual variability analysis revealed that individualswith earlier midpoints of sleep tended to exhibit higher energy levels (beta=-.26, P=.04). Conclusions: Increased sleep variabilities, characterized by unstable bedtime or midpoint of sleep, were correlated with elevatedstress levels and diminished well-being. Conversely, improved sleep indices (eg, lower heart rate during sleep and earlier averagebedtime) were associated with heightened daytime energy levels. Further research with a larger sample size using thesemethodologies, particularly focusing on specific phenomena such as social jet lag, has the potential to yield valuable insights.