Diurnal fluctuation of sleep propensity across the menstrual cycle.

Most women experience sleep changes across the menstrual cycle. We applied the ultra-short sleep–wake schedule to healthy females to compare their 24-h sleep propensity rhythms in the follicular and luteal phases. The daytime (09.00–16.30 h) subjective sleepiness and the number of slow wave sleep-containing nap trials increased in the luteal phase compared to the follicular phase, but the mean sleep propensity did not change. During the periods of 17.00–00.30 h and 01.00–08.30 h there were no differences between the two phases. These results suggest that increased daytime sleepiness in the luteal phase may be related to brain mechanisms controlling slow wave sleep. [ABSTRACT FROM AUTHOR]