http://www.standard.co.uk/lifestyle/health/trouble-sleeping-it-might-be-your-body-s-way-of-protecting-you-from-nocturnal-threats-a3586426.html

Trouble sleeping? It might be your body’s way of protecting you from nocturnal threats

Researchers say that bad sleep may be an evolutionary survival tool

As you get older, getting a good night’s kip seems harder and harder.

But what many might blame on smartphones and stress actually may be an evolutionary survival tool, designed to help protect us from nocturnal threats, researchers say.

While studying modern hunter-gatherers in Tanzania, scientists from the Duke University in South Carolina found differences in age-related sleep patterns has one very big benefit: it ensures that at least one person in a tribe is awake at all times.

This means that they can be on the lookout for potential danger, while the rest of the group sleeps.

Over the three-week period that researchers studied the tribe, there were only 18 minutes when all 33 tribe members were asleep simultaneously.

The scientists concluded that experiencing restless nights sleep as you get older could be an ancient evolutionary trait from thousands of years ago when humans would have to keep watch for predators.

‘The idea that there’s a benefit to living with grandparents has been around for a while, but this study extends that idea to vigilance during nighttime sleep,’ said study co-author Dr David Samson of the Duke University in Durham, South Carolina.

The study looked at the Hadza people in northern Tanzania – who hunt and gather for their food in the same way that humans used to before farming.

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The tribes live and sleep in groups of 20 to 30 people.

In the daytime, the men and women split into separate groups to forage for berries, nuts, tubers and meat in the woodlands surrounding Tanzania’s Lake Eyasi.

As night sets in, they reunite at their camp, where everyone beds down for the evening next to a fire or together in huts made of woven grass and branches.

“They tell an important part of the human evolutionary story because they live a lifestyle that is the most similar to our hunting and gathering past,” said Alyssa Crittenden, an associate professor of anthropology at the University of Nevada, Las Vegas. “They sleep on the ground and have no synthetic lighting or controlled climate.”

Researchers have also found similar patterns in birds and mice, but this is the first time the scientists have recorded the phenomenon in humans.

The scientists believe the theory could be the reason why many elderly people experience insomnia.

“A lot of older people go to doctors complaining that they wake up early and can’t get back to sleep,” co-author Charlie Nunn, professor of evolutionary anthropology at Duke said. “But maybe there’s nothing wrong with them. Maybe some of the medical issues we have today could be explained not as disorders, but as a relic of an evolutionary past in which they were beneficial.”

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