Diurnal sex differences in the sleep-wake cycle of mice are dependent on gonadal function.
OBJECTIVE
Sex is an important determinant of the pathophysiology of several disorders that influence and/or impair sleep-wake regulation. To date, few studies have examined either the role of sex or the gonadal hormones on sleep and wakefulness. The difficulty in performing well-controlled clinical experiments on sex and sleep underscores the need for effective animal models to investigate the influence of the gonadal hormones on sleep-wake states. This study describes the influence of sex on sleep and wakefulness in mice, the primary mammalian genetic model for sleep analysis, and tests the hypothesis that gonadal function drives sex differences in sleep-wake states.


METHODS
Electroencephalogram/electromyogram sleep-wake patterns were recorded in intact and gonadectomized male and female C57BL/6J mice maintained on a 14-hour light:10-hour dark schedule. Following a 24-hour baseline recording, mice were sleep deprived during the light phase by gentle handling and given a 10-hour recovery opportunity during the immediate dark phase.


RESULTS
Intact female mice spent more time awake than intact males during 24 hours of baseline recording at the expense of non-rapid eye movement (NREM) sleep. Though the recovery response of NREM sleep was similar between males and females, when examined in reference to baseline levels, females exhibited a more robust recovery response. Gonadectomy in males and females reduced or eliminated the majority of sex differences in sleep architecture and homeostasis.


CONCLUSIONS
These data demonstrate that the gonadal hormones influence the amount, distribution, and intensity of sleep but do not account for all sex differences in the sleep-wake cycle.
Paul
Ketema N
KN
Neurobiology and Physiology, Northwestern University, Evanston, IL, USA. kpaul@msm.edu
Dugovic
Christine
C
Turek
Fred W
FW
Laposky
Aaron D
AD
D000818:Animals; D002369:Castration / Q000706:statistics & numerical data; D002940:Circadian Rhythm; D004195:Disease Models, Animal; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006066:Gonads / Q000503:physiopathology* / Q000601:surgery; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010052:Ovariectomy / Q000706:statistics & numerical data; D017286:Polysomnography; D012737:Sex Factors; D012892:Sleep Deprivation / Q000453:epidemiology; D020178:Sleep Disorders, Circadian Rhythm / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*