Associations between physical activity, sedentary time, sleep duration and daytime sleepiness in US adults

Objective. To examine the associations between objectively measured physical activity (PA) or sedentary behavior and self-reported sleep duration or daytime sleepiness in a nationally representative sample of healthy US adults (N = 2128). Methods. We report analyses of four aspects of sedentary behavior and PA derived from accelerometry data (minutes of sedentary time, activity counts/minute, Minutes of Moderate and Vigorous PA [MVPA], and MVPA in 10-minute bouts) versus self-report of sleep duration and frequency of daytime sleepiness from the 2005-2006 National Health and Nutrition Examination Survey. Results. Age and sex dependence of associations between PA and sleep were observed. Aspects of PA were significantly lower in adults reporting more frequent daytime sleepiness in younger (20-39) and older (>= 60) age groups, but not in middle-aged (40-59), respondents. In younger respondents, PA increased with sleep duration, but in middle aged and older respondents PA was either unrelated to sleep duration or lower in those reporting >= 8 h of sleep. Objectively measured sedentary time showed limited evidence of associations with sleep duration. Conclusions. Further research delineating the relationships between sleep and PA is important because both activities have been implicated in diverse health outcomes as well as in the etiology of obesity. Published by Elsevier Inc.