Abstract Objectives: Many Japanese adults experience poor sleep quality. Prolonged sedentary behavior negatively affects health, including sleep-associated problems. We investigated the association between sedentary behavior and sleep quality among urban white-collar workers with metabolic syndrome or at risk of metabolic syndrome in Japan, a population thought to have particularly prolonged sedentary time. Methods: This study was conducted under a prospective cohort study design as a secondary analysis of participants data in a lifestyle intervention program using smartphone application in 5 different companies (1000 employees) in Tokyo from December 2018 to March 2019. The primary outcome was sleep quality, obtained as the daily score of relevant items in the St. Mary’s Hospital Sleep Questionnaire (SMHSQ) during the study period. The primary exposure was daily sedentary time (hour), which was objectively measured using a wristwatch-type wearable device (Fitbit Versa). Multilevel linear mixed effects analysis adjusted for covariates was used to estimate between-person and within-person associations. Sensitivity analyses were used to investigate between-/within-person associations between sedentary time and the scores of each item related to sleep quality on the SMHSQ. Results: A longer sedentary time was inversely associated with the SMHSQ scores related to sleep quality in multivariable-adjusted models at the individual level (β coefficient -0.046, Standard error 0.016, 95% CI -0.077 to -0.015). Longer sedentary time was also inversely associated with each sleep satisfaction-related SMHSQ item. However, no significant associations were observed at the population level. Conclusions: Longer sedentary time was inversely associated with sleep quality at the individual level.
Ishikawa et al. (Thu,) studied this question.