Study finds naps aren't all that helpful after a sleepless night

While many of us crave a daytime nap after little sleep during the night, it seems it might not be as useful in helping our concentration and work ability as we thought.

A bad night's sleep every now and then won't have any lasting health consequences other than making you irritable, fatigued and unable to concentrate.

Researchers found that daytime naps after a sleepless night won't improve work performance or concentration as once believed. Photo: Getty
Researchers found that daytime naps after a sleepless night won't improve work performance or concentration as once believed. Photo: Getty

Researchers from Michigan State University had 280 volunteers complete a cognitive test in their labs with some allowed to go home and others were kept awake overnight.

The next day, some of the sleep-deprived participants were allowed to have a 30 minute or one hour nap, before all the participants took another cognitive test.

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Unsurprisingly, those who were kept awake overnight performed worse than those who went home to sleep, but the nappers also performed just as badly.

"We are interested in understanding cognitive deficits associated with sleep deprivation," said study author Dr Kimberly Fenn.

"In this study, we wanted to know if a short nap during the deprivation period would mitigate these deficits.

It seems as though short naps in the day aren't all that helpful for concentration. Photo: Getty
It seems as though short naps in the day aren't all that helpful for concentration. Photo: Getty

"We found short naps of 30 or 60 minutes did not show any measurable effects."

The cognitive tests saw the participants tested on their attention skills and their ability to complete a series of steps in a specific order, without skipping or repeating them.

"The group that stayed overnight and took short naps still suffered from the effects of sleep deprivation and made significantly more errors on the tasks than their counterparts who went home and obtained a full night of sleep," said Dr Fenn.

While napping didn't help in these tests, it can boost what's known as slow-wave sleep (SWS), which is considered the deepest and most restorative stage of sleep.

It's the stage where the body is most relaxed and the heart rate and breathing rates slow.

"SWS is the most important stage of sleep," said Dr Fenn.

"When someone goes without sleep for a period of time, even just during the day, they build up a need for sleep. In particular, they build up a need for SWS."

The results showed "every 10-minute increase in SWS reduced errors after interruptions by about four per cent", according to Dr Fenn.

While four per cent doesn't sound like much, it could be significant in certain jobs where employees are often sleep-deprived or work shifts.

"Individuals who obtained more SWS tended to show reduced errors on both tasks, however, they still showed worse performance than the participants who slept," she said.

The researchers hope their research will encourage people to prioritise sleep and not rely on short naps. If you are going to nap, however, try to get longer than an hour, they said.

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