title: Association between actigraphic sleep metrics and body composition.
abstract: OBJECTIVE
  Determine if individuals with poor sleep characteristics (i.e., late sleep onset or wake times, short sleep duration, long sleep latency, low sleep efficiency, high wake after sleep onset) have greater body mass index (BMI = kg/m(2)) or body fat.
  
  
  METHODS
  Data for these cross-sectional analyses were from the Energy Balance Study (University of South Carolina). Participants were between 21 and 35 years of age and had a BMI of 20 to 35 kg/m(2). Body fat percent was measured by dual X-ray absorptiometry. Sleep and physical activity were measured by actigraphy (BodyMedia's SenseWear physical activity armband). General linear models were used to estimate mean BMI and body fat percent by sleep metric categories.
  
  
  RESULTS
  Greater BMI and body fat percent were associated with low sleep efficiency (BMI = 25.5 vs. 24.8 kg/m(2), P < .01; body fat = 27.7% vs. 26.5%, P = .04) and high wake after sleep onset (BMI = 25.6 vs. 25.0 kg/m(2), P = .02; body fat = 28.0% vs. 26.7%, P = .03). Elevated BMI or body fat percent also were observed for later wake times, shorter sleep duration, and longer sleep latency. Sex modified the association between wake times and body composition.
  
  
  CONCLUSIONS
  Understanding the complex relationships between sleep and health outcomes could help reduce chronic disease burden by incorporating sleep components, measured through novel noninvasive techniques (SenseWear armband), into weight loss interventions.
authors.affiliation: South Carolina Statewide Cancer Prevention and Control Program, University of South Carolina, Columbia; Department of Epidemiology and Biostatistics, University of South Carolina, Columbia. Electronic address: wirthm@mailbox.sc.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Wirth
authors.affiliation: South Carolina Statewide Cancer Prevention and Control Program, University of South Carolina, Columbia; Department of Epidemiology and Biostatistics, University of South Carolina, Columbia.
authors.forename: James R
authors.initials: JR
authors.lastname: Hébert
authors.affiliation: Department of Epidemiology, West Virginia University, Morgantown.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Hand
authors.affiliation: College of Nursing and Health Innovation, Arizona State University, Phoenix; College of Health Solutions, Arizona State University, Phoenix.
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Youngstedt
authors.affiliation: South Carolina Statewide Cancer Prevention and Control Program, University of South Carolina, Columbia.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Hurley
authors.affiliation: Department of Kinesiology, Iowa State University, Ames.
authors.forename: Robin P
authors.initials: RP
authors.lastname: Shook
authors.affiliation: Department of Exercise Science, University of South Carolina, Columbia.
authors.forename: Amanda E
authors.initials: AE
authors.lastname: Paluch
authors.affiliation: Department of Exercise Science, University of South Carolina, Columbia.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Sui
authors.affiliation: Department of Epidemiology, West Virginia University, Morgantown.
authors.forename: Shelli L
authors.initials: SL
authors.lastname: James
authors.affiliation: Department of Epidemiology and Biostatistics, University of South Carolina, Columbia; Department of Exercise Science, University of South Carolina, Columbia.
authors.forename: Steven N
authors.initials: SN
authors.lastname: Blair
mesh_terms: D015502:Absorptiometry, Photon; D056044:Actigraphy; D000273:Adipose Tissue; D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D050177:Overweight / Q000453:epidemiology; D012737:Sex Factors; D012890:Sleep; D012893:Sleep Wake Disorders / Q000453:epidemiology*; D013997:Time Factors
keywords: Abdominal fat; Absorptiometry; Actigraphy; Body mass index; Sleep