Effects of physical activity on sleep in an ecologically valid design.

BACKGROUND

Both sleep and physical activity (PA) are essential for health. Previous studies found inconsistent effects of PA, including evening PA (EPA), on sleep.

PURPOSE: To examine the effects of PA and its timing on objectively and subjectively measured sleep in predominantly healthy, young adults.

METHODS

In the Budapest Sleep, Experiences and Traits Study, a highly ecologically valid multiday observational study, 267 participants tracked their natural sleep and reported PA for at least 1 week, including mobile electroencephalography recordings. We estimated the effects of PA and its timing, quantifying it as the time elapsed between activity initiation and sleep onset.

RESULTS

Our findings showed no substantial main effect of PA on sleep (all P ≥ .19). However, PA temporally close to sleep had a rapid eye movement (REM) sleep-suppressing effect: each additional hour between PA and sleep onset decreased REM latency by 1.8 minutes (B = -1.82, SE = 0.58, P = .002) and increased REM percentage by 0.30 percentage points (B = 0.30, SE = 0.11, P = .008), but no other timing effect was found. Results were robust across multiple analytical specifications.

CONCLUSIONS

Our results support neither a general sleep-promoting effect of PA nor a sleep-suppressing effect of EPA and suggest that for healthy young individuals, habitual, relatively low-intensity EPA is safe to perform and is a good alternative for those whose daily schedule permits no alternative timing, although the lack of detailed exercise intensity monitoring is a limitation of our study.