title: Relationship between actigraphy-assessed sleep quality and fat mass in college students.
abstract: OBJECTIVE
  Only a few studies have used objective measurements to investigate the relationship between sleep quality and obesity. These studies showed controversial results.
  
  
  METHODS
  Sleep efficiency was measured by Actiwatch 2 in 132 healthy students (age 23.3 ± 3.7 years, BMI 23.1 ± 4.1 kg/m(2) ) for 12 ± 3 nights, differentiating between work and free days. Physical activity, dietary habits, and autonomic function (heart rate variability, HRV) were analyzed as potential determinants of sleep quality and its relationship with body composition.
  
  
  RESULTS
  Sleep efficiency was 87.0% in women and 84.9% in men (P < 0.05) and was higher at free days when compared to work days in women (P < 0.05). Lower sleep efficiency was associated with a higher fat mass. This was true for sleep efficiency on work days in women [fat mass index (FMI): r = -0.35, P < 0.01] and for free days in men (FMI: r = -0.37, P < 0.05). Poor sleep efficiency was associated with less physical activity (r = 0.29, P < 0.05) and impaired HRV in women (r = 0.60, P < 0.05) and with a higher fat intake in men (r = -0.39, P < 0.05).
  
  
  CONCLUSIONS
  Poor sleep efficiency was associated with higher fat mass. The relationship between sleep quality and fat mass differs between work and free days and may be explained by physical activity and autonomic function in women and dietary habits in men.
authors.affiliation: Institute of Nutritional Medicine, University Hohenheim, Stuttgart, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Kahlhöfer
authors.affiliation: Institute of Nutritional Medicine, University Hohenheim, Stuttgart, Germany.
authors.forename: Judith
authors.initials: J
authors.lastname: Karschin
authors.affiliation: Institute of Nutritional Medicine, University Hohenheim, Stuttgart, Germany.
authors.forename: Nicolle
authors.initials: N
authors.lastname: Breusing
authors.affiliation: Institute of Nutritional Medicine, University Hohenheim, Stuttgart, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Bosy-Westphal
mesh_terms: D056044:Actigraphy / Q000379:methods; D000328:Adult; D001823:Body Composition; D004734:Energy Metabolism; D005247:Feeding Behavior; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009765:Obesity / Q000503:physiopathology*; D012890:Sleep / Q000502:physiology; D007319:Sleep Initiation and Maintenance Disorders / Q000503:physiopathology*; D013334:Students / Q000706:statistics & numerical data*; D055815:Young Adult