Relationships between sleep, exercise timing, and chronotype in young adults.

To examine the relationships between exercise timing, chronotype, sleep, and mood, college students (N = 909, 19.6 ± 1.4 years, 38% female) completed questionnaires immediately after exercising. Evening exercisers had later bedtimes, poorer sleep quality, and lower sleep efficiency compared to morning exercisers. Evening chronotypes reported poorer sleep quality, greater daytime dysfunction, and less positive affect compared to morning/neither chronotypes. Chronotype moderated the relationship between exercise timing and bedtime; with each minute delay in exercise timing, bedtime was delayed by 6.1 minutes in morning-types and only 3.6 minutes in evening-types. University health initiatives should target evening exercisers to mitigate the consequences of prolonged insufficient sleep.