New stats suggest women are more likely to be affected by night shiftwork than men.

Experts from the University of Surrey joined with colleagues from the UK and Singapore for a research project that looked at the ability to perform tasks accurately when working night shifts.

The study details how changes in sleep-wake cycles and circadian rhythms can influence brain function in men and women, for the first time.

The research team rescheduled the sleep-wake cycles of 16 men and 18 women into a 28-hour day, so they would go to bed and wake four hours later each day.

For ten days, all indicators of time including external light were removed from the laboratory, while ‘waking hours’ were marked by low-light conditions.

Sydney Uni researcher Dr Derk-jan Dijk explains that sleep is regulated by two bodily systems — the sleep-wake cycle and the circadian biological clock.

The sleep-wake cycle balances sleep throughout the night to against time awake, while the circadian clock controls sleepiness and wakefulness on either side of the night.

While the body’s circadian clock adjusts based on environmental time and light levels, most adults’ strongest drive to sleep comes between 2am and 4am.

By shifting to a 28-hour day, the sleep-controlling mechanisms were disrupted. This let researchers determine the impact of the body’s clocks on performance.

Participants performed cognitive tasks and self-assessments every three hours while they were awake, including ranking their sleepiness, mood and effort required to complete tasks, as well asd tests of attention, accuracy and motor control.

The study showed that women’s performance on certain tasks was more impaired by “being awake at the wrong time of day” than for men.

“Extrapolation of these findings to the real world implies that women may be more affected by shiftwork than men,” Dr Dijk said.

The researchers suggested the difference “may in part reflect social factors such as family and childcare responsibilities that lead women to work longer hours and to sleep less on days off than men”.

The full study is available here.