Research already suggests that working night shifts may increase your risk of certain health problems, such as sleep disorders, heart disease and diabetes. However a new study indicates that women may be more affected by working unsocial hours than men.

According to UK researchers, the findings could have implications for female night shift workers such as nurses and police officers.

The study involved putting 16 male and 18 female adults on 28-hour days in a controlled environment. The participants were not exposed to natural light-dark cycles. This basically changed their sleep-wake cycle from the brain's usual 24-hour body clock - known as the circadian clock - making the body feel like it was jetlagged or in a shift work situation.

During their awake time, the participants performed a range of tests every three hours. These assessed things like their mood and cognitive performance, such as attention span and memory skills. The participants' brains were also monitored continually while they slept.

The study found that this change to the circadian clock was much stronger in women than in men. Women were more cognitively impaired during the early morning hours, which in a real-world scenario 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. Our research findings are significant in view of shift work-related cognitive deficits and changes in mood. Extrapolation of these results would suggest that women may be more affected by night shift work than men," commented the study's co-author, Dr Nayantara Santhi, of the University of Surrey.

The researchers acknowledged that the results show that changes in the circadian clock affect the brain function of both men and women, but these effects ‘differ between the sexes in a quantitative manner for some measures of brain function'.

Details of these findings are published in the journal, PNAS (Proceedings of the National Academy of Sciences).