title: A reassessment of the hyperphagia/weight-loss paradox during sleep deprivation.
abstract: OBJECTIVE
  Sleep deprivation is a well-known paradigm to investigate the deleterious effects of prolonged wakefulness. Previous studies have shown that, during sleep deprivation, rats are hyperphagic but, paradoxically, lose body weight. This phenomenon has been attributed to increased metabolism. However, most previous studies have failed to account for food spillage, which may be considerable during sleep deprivation.
  
  
  METHODS
  In the present study, we revisited the issue of feeding changes in sleep-deprived rats and introduced different procedures to allow accurate estimation of food spillage prior to, during, and after 120 hours of sleep deprivation by a single platform technique.
  
  
  METHODS
  Animal Sleep Research Laboratory, Psychobiology Department, Universidade Federal de São Paulo, Brazil.
  
  
  RESULTS
  The main finding was that, once corrected for spillage, food intake was not significantly increased during sleep deprivation. Increases in food removed from feeders were accompanied by proportional increases in food spillage, resulting in no net changes in food intake. Further, weight loss did occur during the sleep-deprivation period, especially in the first 24 hours, and it was actually explained by a reduction in food intake.
  
  
  CONCLUSIONS
  The hyperphagia/weight-loss paradox previously seen during prolonged sleep deprivation does not necessarily occur with shorter periods of deprivation. Although we found no evidence of hyperphagia for up to 5 days of sleep deprivation in chow-fed rats, our data suggest that an impairment in the ability to increase food intake in response to increased energy expenditure contributes to the energy deficit during sleep deprivation in rats.
authors.affiliation: Department of Psychobiology of Universidade Federal de São Paulo-UNIFESP, São Paulo, Brazil. pmartins@psicobio.epm.br
authors.forename: Paulo J F
authors.initials: PJ
authors.lastname: Martins
authors.forename: Vânia
authors.initials: V
authors.lastname: D'Almeida
authors.forename: José N
authors.initials: JN
authors.lastname: Nobrega
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002149:Energy Intake; D005247:Feeding Behavior; D006963:Hyperphagia / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012892:Sleep Deprivation / Q000175:diagnosis* / Q000453:epidemiology*; D015431:Weight Loss