Increased vulnerability to attentional failure during acute sleep deprivation in women depends on menstrual phase.

STUDY OBJECTIVES

To investigate sex differences in the effect of sleep deprivation on performance, accounting for menstrual phase in women.

METHODS

We examined alertness data from 124 healthy women and men (40 women, 84 men; aged 18-30 years) who maintained wakefulness for at least 30 hr in a laboratory setting using a constant routine protocol. Objective alertness was assessed every 2 hr using a 10 min psychomotor vigilance task. Subjective alertness was assessed every hour via the Karolinska Sleepiness Scale.

RESULTS

Women in the follicular phase of the menstrual cycle demonstrated the poorest level of performance. This poor performance was most pronounced at times corresponding to the typical sleep episode, demonstrating a window of vulnerability at night during this menstrual phase. At 24 hr awake, over 60 per cent of their responses were lapses of >500 ms and over one-third of their responses were longer lapses of at least 3 s in duration. Women in the luteal phase, however, were relatively protected from alertness failure, performing similar or better than both follicular-phase women and men.

CONCLUSIONS

These results have important implications for education and intervention programs for shift workers, specifically during times of vulnerability to attentional failure that increase risk of injury.