Physical Activity Frequency Patterns Influence Sleep Architecture in Young Adults

Background : Physical activity is associated with sleep quality and changes in sleep stages. Few studies have explored specific physical activity prescription parameters for informing behavioral interventions for sleep. This secondary data analysis explores how physical activity frequency and intensity are associated with sleep architecture. Methods : Sixty-nine adults (mean age = 21.5 y, 63% female) wore a wrist-mounted fitness monitor to measure physical activity and sleep for 2 data collection intervals spanning a total of 8 months. Participants received triweekly electronic surveys asking to rank their levels of energy, stress, contentment, and sleep quality in the morning. Mixed effects linear models were used to determine the effects of physical activity frequency and intensity (light or moderate to vigorous) on sleep architecture, sleep quality, and mood. Results : Having more days with at least 10 minutes of moderate- to vigorous-intensity physical activity within a 5-day period was associated with a lower rapid eye movement/nonrapid eye movement ratio in the first 180 minutes of sleep ( β = −0.18, P = .018). Total light-intensity physical activity was associated with the same effect ( β = −0.16, P = .048), as well as higher morning energy levels ( β = 0.16, P = .047). Within a day, the proportion of hours with at least 3 minutes of light-intensity physical activity was associated with greater sleep time and a lower rapid eye movement/nonrapid eye movement ratio in the first 360 minutes of sleep ( β = 0.10, P = .049; β = −0.15, P = .022). The proportion of hours with at least 3 minutes of moderate- to vigorous-intensity physical activity was associated with morning contentment ( β = 0.13, P = .049). Conclusions : This study suggests that the effects of physical activity on sleep are carried over across the week and identifies intraday and interday frequency to be important factors for consideration in physical activity interventions for improving sleep.