Mood and Sleep. I. Effects of the menstrual cycle.

Four female subjects were studied during eight nights each at corresponding days of the menstrual cycle. No clear cycle effects could be discerned in the sleep variables of the subjects as a group. In one subject, however, a U-shaped course of negative mood was found during the menstrual cycle, together with an enhanced percentage of stage 2 sleep and a lowered percentage of slow wave sleep at the time of the menses. In the three other subjects' cycles no such cyclic variations in the mood or sleep variables were found.