Relationship Between Sleep and Next Day Physical Activity

Objective The purpose of this study was to examine the effect that sleep duration and quality has on next day physical activity among a population of young adult women. Subjects: Three-hundred and seventy-five women (18-24 yrs) were recruited to participate in the study.

Measurements Each participant wore an accelerometer for 7 consecutive days and nights to measure sleep and physical activity. Sleep logs were used to verify the bedtime and wake time for each night. Actigraph data was then evaluated to determine sleep latency, efficiency, and number of awakenings. Physical activity data was also evaluated for intensity (sedentary, light, Moderate and Vigorous) and duration.

Results Two thousand six hundred and forty one observations were collected and 2144 observations were used. There was an inverse relationship between total sleep time and next day activity (F = 102.76, p < 0.0001). However, controlling for wake time reduced the magnitude of the relationship by 92%. Wake time was the best predictor of next day physical activity (F = 202.02, p < 0.0001). There was a significant drop in physical activity for every hour after 7:30 in the morning that the participants got out of bed (F = 32.24, p < 0.0001). While sleep efficiency did not correlate with overall activity, it did show an inverse relationship with light activity (F = 48.94, p < 0.0001) and a positive relationship with sedentary activity (F = 39.73, p < 0.0001).

Conclusions Sleep duration and more specifically, time getting out of bed are related to next day physical activity. Arising earlier in the morning may significantlyincrease physical activity, which may be due to simply having more time to be active during the day.