The conversations of life

Ever wondered why you sleep less as you age? To save you from being eaten by lions


It’s true. A new US study has shown we may have actually evolved to sleep less as we get older so we can survive in dangerous environments.

The research, which looked at a group of hunter-gatherers in Tanzania, Africa with similar sleeping patterns to our earliest ancestors, found that when family members of different ages live together, at least one person is always awake to protect against predators.

And it’s not because they have a guard on watch at night. Rather the families naturally had different sleeping patterns that meant on average, around one-third of the healthy adults were alert or dozing at any one time.

In total, there was only 18 minutes when no one was awake over the 20 days of the study.

And in general older participants in their 50s and 60s went to bed earlier and woke up earlier than those in their 20s and 30s. Yet none complained about a lack of sleep.

“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 night-time sleep,” said study co-author David Samson.

So if you’re having a restless night? Blame those cavemen – and the grandkids.

Lauren is a journalist for, agedcare101 and The Donaldson Sisters. Growing up in a big family in small town communities, she has always had a love for the written word, joining her local library at the age of six months. With over eight years' experience in writing and editing, she is a keen follower of news and current affairs with a nose for a good story.

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