title: Circadian rhythm of rectal temperature during sleep deprivation with modafinil.
abstract: BACKGROUND
  Sleep deprivation (SD) induces many adverse psychological and physiological effects, particularly on vigilance and the thermoregulatory system. The drug modafinil appears to suppress or diminish the harmful effects on vigilance. However, the effects of modafinil combined with SD on the circadian rhythm of core temperature are not well established.
  
  
  OBJECTIVE
  We studied the circadian rhythm of rectal temperature (CRTre) during 62 h of SD alone or with three dosage levels of modafinil.
  
  
  METHODS
  Six men underwent repeated SD experiments lasting 7 d each, including a 24-h control period, 62 h of SD, and a 24-h recovery period. Experiments were repeated four times in mixed order for placebo and three levels of modafinil (50, 150, or 300 mg x 24 h(-1)). The Tre was recorded each minute throughout the experiment and the CRTre was studied by the single cosinor method.
  
  
  RESULTS
  Independent of modafinil, SD increased the mesor (p < 0.05) and reduced the amplitude (p < 0.01) of the CRTre without changing the acrophase. During the recovery period, a rebound increase was seen in the amplitude of the CRTre (p < 0.01). The 50 mg x 24 h(-1) dose of modafinil, but not the higher doses, induced a lower mesor (p < 0.01) independent of SD.
  
  
  CONCLUSIONS
  The observed changes may reflect a threshold for the central action of modafinil on core temperature. The hyperthermic effect reported in the literature for SD with modafinil may actually result from the sleep deprivation alone.
authors.affiliation: jclaunay@crssa.net
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Launay
authors.forename: Gustave
authors.initials: G
authors.lastname: Savourey
authors.forename: Angélique
authors.initials: A
authors.lastname: Guinet
authors.forename: Guy
authors.initials: G
authors.lastname: Lallement
authors.forename: Yves
authors.initials: Y
authors.lastname: Besnard
authors.forename: Jacques
authors.initials: J
authors.lastname: Bittel
mesh_terms: D000328:Adult; D001559:Benzhydryl Compounds / Q000494:pharmacology*; D001831:Body Temperature / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002940:Circadian Rhythm; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D000077408:Modafinil; D012007:Rectum; D012892:Sleep Deprivation / Q000139:chemically induced* / Q000503:physiopathology
chemical_list: D001559:Benzhydryl Compounds; D000697:Central Nervous System Stimulants; D000077408:Modafinil