Increased Steps in Japanese Older Adults Associated with Improved Winter Sleep Quality.

Objective: We aimed to assess seasonal and age-related variations in sleep quality using Fitbit data and offer lifestyle recommendations for enhancing winter sleep quality. Methods: Fitbit sleep and activity data of 51 participants randomly recruited from members of the Association for Research in Supporting System of Chronic Disease, a nonprofit organization in the Yamanashi Prefecture of Japan, were collected and retrospectively analyzed from July to December 2022. Sleep stage targets were set at 10% to 25% for deep sleep, 50% to 60% for shallow sleep, and 20% to 25% for REM sleep. Participants were categorized into improved, unchanged, and worsened groups based on sleep stage unit changes between August and December. Results: The median (interquartile range) age was 71 (68-74) years old. There were eight participants in the improved group, 23 in the unchanged group, and nine in the worsened group. The improved group showed significantly more steps (990 ± 1,102 steps/day, p = .039) in December than in August, while the worsened group showed fewer steps (-507 ± 1,638 steps/day, p = .38). Conclusion: Increasing step count in winter may improve sleep quality, as assessed by sleep stage. Further research considering potential confounders and factors affecting winter sleep is needed to support and extend these findings.