SLEEP - How Much Do You Really Need?

"These hunter-gatherer tribes sleep less than you, and sleep better" PBS NewsHour 10/15/2015

Excerpt

SUMMARY:  By studying the habits of three hunter-gatherer groups who live much the way humans have for thousands of years, a team of scientists is challenging conventional wisdom about how much sleep we need.  Hari Sreenivasan goes to UCLA to learn more about getting enough rest and to do something he's never done on assignment before: falling asleep while on the job.

HARI SREENIVASAN (NewsHour):  ..... just how much sleep do you really need?  There’s been plenty of concern, as people spend more time looking at their screens ever later into the night.

Previous research has shown that a lack of sleep is associated with a series of problems, ranging from lack of concentration to health effects like obesity and heart disease.

But a new study out today finds seven or eight hours a night may not be as essential as we think.

I went to California to learn more.

They are among the last hunter-gatherers in the world, the Hadza of Northern Tanzania, the San of Namibia’s Kalahari Desert, and in the Andean foothills of Bolivia the Chimane.

By studying the sleep habits of these three groups, who still live the way humans have for thousands of years, a team of scientists led by UCLA’s Jerry Siegel is challenging conventional wisdom about how much sleep we need.

JERRY SIEGEL, Director, UCLA Center for Sleep Research:  It’s absolutely incorrect to think that the more you sleep, the healthier you’re going to be.

HARI SREENIVASAN:  The study, reported today in the journal “Current Biology” says we in the industrialized world sleep as much as our ancestors did.

JERRY SIEGEL:  There’s been speculation that humans basically used to sleep when it got dark, which would mean they’d sleep 10, 11, even 12 hours.  But it turns out that’s not the case.  These groups sleep five, six, seven hours.  None of them average over eight hours of sleep.

HARI SREENIVASAN:  Just like us, when the sun sets, these people do not go right to sleep.

JERRY SIEGEL:  There’s a thin yellow line here that indicates the light level, and you can see also that they remain awake.

HARI SREENIVASAN:  In fact, regardless of what time they go to bed, all three groups, on different parts of the planet, wake up exactly when one very specific thing happens.  And, no, it’s not the sunrise.

JERRY SIEGEL:  They’re sleeping as the temperature falls, and they seem to quite consistently wake up at the lowest point of temperature in the day.  So, when the temperature stops falling, that’s when they wake up.

There’s been a lot of emphasis on light and the effects of light, and there’s no question that light affects sleep.  But light may have been connected to sleep largely because of its connection to temperature.