Circadian rhythm of rectal temperature during sleep deprivation with modafinil.
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.
Launay
Jean-Claude
JC
jclaunay@crssa.net
Savourey
Gustave
G
Guinet
Angélique
A
Lallement
Guy
G
Besnard
Yves
Y
Bittel
Jacques
J
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
D001559:Benzhydryl Compounds; D000697:Central Nervous System Stimulants; D000077408:Modafinil