title: Associations between physical activity, sedentary time, sleep duration and daytime sleepiness in US adults.
abstract: 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.
authors.affiliation: Applied Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, MD 20892, USA. Electronic address: james.mcclain@nih.gov.
authors.forename: James J
authors.initials: JJ
authors.lastname: McClain
authors.affiliation: Children's National Medical Center, George Washington University School of Medicine, Washington, DC 20310, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Lewin
authors.affiliation: National Center for Sleep Disorders Research, National Heart Lung and Blood Institute, Bethesda, MD 20892, USA.
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Laposky
authors.affiliation: Information Management Services, Inc., Calverton, MD, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Kahle
authors.affiliation: Applied Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: David
authors.initials: D
authors.lastname: Berrigan
mesh_terms: D061725:Accelerometry; D000328:Adult; D000367:Age Factors; D015444:Exercise / Q000502:physiology*; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D057185:Sedentary Behavior; D012890:Sleep; D012892:Sleep Deprivation; D014481:United States; D055815:Young Adult
keywords: Accelerometry sleepiness; Age; Physical activity; Sedentary time; Sex; Sleep; Sleep duration