Sex differences in the polysomnographic sleep of young adults: a community-based study

In small, clinical samples, men have reduced slow wave sleep compared to women. Given the higher prevalence of sleep-related breathing disturbance in men, this study assessed sex differences in sleep in a large, non-clinical sample of adults and controlled for primary sleep disorders.

Men and women, 31-40 years old, drawn from a longitudinal sample representative of southeast Michigan served as subjects. Each underwent a sleep study consisting of two consecutive 8-h nights of standard polysomnography (NPSG) and a multiple sleep latency test (MSLT) the intervening day.

Of the 439 eligible participants, 292 (66.5%) agreed to spend two consecutive nights and the intervening day in the sleep laboratory. Standard polysomnograms that monitored respiration and leg movements were collected each night, and on the intervening day the MSLT was performed. Men had more sleep-related breathing disturbance than women. After adjusting for this higher prevalence of respiratory disturbance, men still had a lower mean sleep efficiency (i.e. increased wake time) and a higher percentage of stage 1 sleep. Men and women did not differ in most other sleep parameters and did not differ in level of daytime sleepiness on the MSLT.

Sleep-related respiratory disturbance accounted for some of the sex differences in sleep. After correcting for respiratory disturbance, men still had lighter and less efficient sleep, but this was not associated with greater daytime sleepiness. Whether this reflects a sex difference in the functioning of the sleep homeostat will require further study.