To evaluate changes in sleep across the phases of the menstrual cycle, sleep-wake diaries were completed by 32 healthy women twice daily for 2 menstrual cycles. There was a significant increase in sleep onset latency and a significant decrease in sleep efficiency and sleep quality during the luteal phase. This increase in sleep disturbance was observed in the entire sample and was not related to the severity of other premenstrual symptoms. However, women having increased severity of other premenstrual symptoms reported greater luteal increase in daytime sleepiness. Thus, although menstruating women are likely to show increased sleep disturbance during the luteal phase, those with other, more severe premenstrual symptoms are more likely to experience a luteal increase in daytime sleepiness.