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Published: 04 May 2016

Night shifts may be more disruptive to women than men, brain study suggests

New research at Surrey suggests disrupted sleep patterns could have more impact on some measures of women's performance than men's.

We put our partcipants on a 28-hour sleep-wake cycle of activities and, without any cues about what the actual time was, their brain clock’s natural rhythm became out of sync with their sleep-wake schedule. Their sleeping and waking times were at odds with their brain clock’s night and day, just as happens when people work night shifts.

Every three hours while the participants were awake, we tested their attention, memory and motor control skills, and asked them to rate the effort they needed to complete the tasks, as well as their sleepiness and mood. Because the participants' sleep-wake cycle was different from that of their brain clocks, they were sometimes asked to perform when their brain thought it was night and sometimes during the brain’s day.

Skills decline

The results showed that many aspects of waking performance are influenced by the brain clock. Generally, performance across the skills we tested was poorer during the brain’s night than during its day. Performance also became worse the longer the participants had been awake.

These effects were more noticeable for self-reported measures such as sleepiness than for some objective measures such as working memory, in both men and women. But we also found that, on average, performance declined more in the women than the men, particularly in the early morning after having been awake for a long time, just as people might experience during a 12-hour shift, for example.

Our study is a carefully controlled laboratory study in a relatively small group of young men and women so it will be important to do larger studies in real life situations. But its major implication is that our ability to respond to being awake at night – and how that can affect our job performance – could be influenced by individual differences such as our sex.

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This article was originally published on The Conversation.

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