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Published: 16 June 2016

Night shifts may be more disruptive to women than men

A new study from the Surrey Sleep Research Centre at the University has found that night shifts may be more disruptive to women’s sleep-wake cycles than men’s.

Researchers placed 16 male and 18 female participants on 28-hour days in a controlled environment without natural light and darkness. 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 comprised attention span, motor control and working memory.

Brain electric activity (EEG) was monitored continuously during their sleep. The results revealed 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.

Professor Derk-Jan Dijk said: “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. Overall the findings illustrate how important it is to include both men and women in research studies and to use a wide range of subjective and objective indicators of how their brains affected.”

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