title: Resting metabolic rate varies by race and by sleep duration.
abstract: OBJECTIVE
  Short sleep duration is a significant risk factor for weight gain, particularly in African Americans and men. Increased caloric intake underlies this relationship, but it remains unclear whether decreased energy expenditure is a contributory factor. The current study assessed the impact of sleep restriction and recovery sleep on energy expenditure in African American and Caucasian men and women.
  
  
  METHODS
  Healthy adults participated in a controlled laboratory study. After two baseline sleep nights, subjects were randomized to an experimental (n = 36; 4 h sleep/night for five nights followed by one night with 12 h recovery sleep) or control condition (n = 11; 10 h sleep/night). Resting metabolic rate and respiratory quotient were measured using indirect calorimetry in the morning after overnight fasting.
  
  
  RESULTS
  Resting metabolic rate-the largest component of energy expenditure-decreased after sleep restriction (-2.6%, P = 0.032) and returned to baseline levels after recovery sleep. No changes in resting metabolic rate were observed in control subjects. Relative to Caucasians (n = 14), African Americans (n = 22) exhibited comparable daily caloric intake but a lower resting metabolic rate (P = 0.043) and higher respiratory quotient (P = 0.013) regardless of sleep duration.
  
  
  CONCLUSIONS
  Sleep restriction decreased morning resting metabolic rate in healthy adults, suggesting that sleep loss leads to metabolic changes aimed at conserving energy.
authors.affiliation: Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Spaeth
authors.affiliation: Division of Sleep and Chronobiology, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: David F
authors.initials: DF
authors.lastname: Dinges
authors.affiliation: Division of Sleep and Chronobiology, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Namni
authors.initials: N
authors.lastname: Goel
mesh_terms: D000328:Adult; D001741:Black or African American; D001481:Basal Metabolism / Q000502:physiology*; D002153:Calorimetry, Indirect; D002149:Energy Intake / Q000208:ethnology / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D005215:Fasting / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D044469:Racial Groups; D012146:Rest / Q000502:physiology; D012890:Sleep / Q000502:physiology*; D012892:Sleep Deprivation / Q000378:metabolism*; D015430:Weight Gain; D044465:White People; D055815:Young Adult