The study found that shifted sleep-wake cycles affect men and women's brain function differently.
Researchers from University of Surrey in the UK placed 16 male and 18 female participants on 28-hour days in a controlled environment without natural light-dark cycles.
This effectively desynchronised the sleep-wake cycle from the brain's 24-hour (circadian) clock, similar to jet lag or a shiftwork scenario.
Every three hours during the awake period, participants performed a wide range of tests, including self-reported assessments of sleepiness, mood and effort, and objective tests of cognitive performance which included measures of attention, motor control and working memory.
More From This Section
However, the circadian effect on performance was significantly stronger in women than in men such that women were more cognitively impaired during the early morning hours, which in the real world typically coincides with the end of a night shift.
"We show for the first time that challenging the circadian clock affects the performance of men and women differently," said Nayantara Santhi from University of Surrey.
"These results show that in both men and women circadian rhythmicity affects brain function and that these effects differ between the sexes in a quantitative manner for some measures of brain function," said Derk-Jan Dijk from University of Surrey.
The findings were published in the journal PNAS.