Association between late afternoon and early evening physical activity and next-day depression and anxiety symptoms among workers in Japan: a two-week longitudinal study

Abstract Background While physical activity is a preventive factor against depression and anxiety, less is known about how the timing of physical activity throughout the day is associated with improved mental health the next day among workers. This study investigated the association between physical activity in the late afternoon and early evening and next-day symptoms of depression and anxiety among workers. Methods We conducted a secondary analysis of a two-week longitudinal study. Participants were full-time, daytime workers employed in either the private or public sector, residing or working in urban areas of Japan, and owning a personal smartphone. Participants were instructed to install Google Fit app to passively track physical activity. They also completed daily web-based surveys between 5:00 PM and 6:00 PM, using the Japanese K6 scale to assess depression and anxiety symptoms. Physical activity was categorized into two timeframes: late afternoon (3:00 PM to 6:00 PM) and early evening (6:00 PM to 9:00 PM). A K6 score ≥ 5 was classified as a high symptom level for depression and anxiety. Associations were analyzed using generalized linear mixed models, adjusting for age, gender, and previous-day depression and anxiety symptoms. Results A total of 116 participants met the eligibility criteria, contributing 1,400 observation days. A high symptom level for depression and anxiety was reported on 259 days (18.5%). Physical activity in the late afternoon showed a non-significant negative association with next-day depression and anxiety symptoms (OR = 1.00, 95% CI: 0.99–1.01, p = 0.472). In contrast, early evening activity indicated a marginally significant association with lower symptoms (OR = 0.99, 95% CI: 0.97–1.00, p = 0.061). Regarding the covariates, a higher K6 level on the previous day and younger age (≤ 39 years) were significant predictors. Subgroup analyses showed significant negative associations for having low levels of depression and anxiety symptoms on the previous day (K6 score < 5) (OR = 0.98, 95% CI: 0.96–0.997, p = 0.023) during this timeframe. Conclusions Physical activity in the early evening was associated with reduced risk of next-day depression and anxiety symptoms, particularly when prior-day symptom levels were lower.