A new study that compared performance between men and women after experiencing 28-hour schedules, which disrupted their internal 24-hour body clock, found that shifted sleep-wake cycles affect men and women's ability to function differently.
Researchers said that extrapolation of their findings would suggest that women may be more affected by night shift work than men. The study could have significant implications for women who work night shifts in professions such as nursing and the police.
Our body clock, or circadian rhythm, regulates the daily cycles of our bodies as we transition from day to night, and from wakefulness to sleep. A ‘master clock’ in the brain coordinates and syncs the clocks of various different processes, such as hormone production, metabolism and blood pressure.
For the study, the researchers put male and female volunteers on 28-hour days in a controlled sleep lab. This meant that they experienced day-night changes on a 28-hour pattern instead of the 24-hour pattern of their inbuilt circadian rhythm. As the days went on, the participants began to sleep out of sync with their internal clock - similar to what happens when working shifts or due to jet lag, for example.
Subjective and objective tests during the observation period showed that women performed less well during the early morning, which would be around the time a night shift worker comes off a night shift.
The results also showed 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.