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Why a neuroscientist calls lack of sleep our greatest public health challenge

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In his new book, “Why We Sleep: Unlocking the Power of Sleep and Dreams,” neuroscientist Matthew Walker discusses the importance of sleep — for our bodies and our brains.
Alex Friedrich | MPR News file

Lack of sleep is making us sick, fat and dumb, says neuroscientist Matthew Walker. He believes little rest is the greatest public health challenge we face in the 21st Century.

In 1942, the average American adult was sleeping 7.9 hours. A recent survey shows that they are now sleeping about six hours and 31 minutes.

"It took Mother Nature 3.6 million years to put this thing called eight hours of sleep for human beings in place," Walker said. "And then we come along and lop off maybe 25 percent of that within the space of just 75 or 80 years."

That trend has had a serious effect on our health. Deadly diseases, obesity and suicide rates all have a connection to how much sleep we are getting, Walker said.

"Human beings are the only species that deliberately deprive themselves of sleep for no apparent gain," Walker said. "Many people walk through their lives in an under-slept state, not realizing it."

The Centers for Disease Control reports more than a third of American adults don't get enough sleep.

But as scientists are discovering, chronic under-sleeping can cost you big in the long run. Sleep doesn't just contribute to vitality, it resets your brain — and poor sleep has even been linked to Alzheimer's disease and other forms of dementia.

Walker said lack of sleep — defined as six hours or fewer — can have serious consequences. Sleep deficiency is associated with problems in concentration, memory and the immune system, and may even shorten life span.

In his new book, “Why We Sleep: Unlocking the Power of Sleep and Dreams,” Walker discusses the importance of sleep and offers strategies for getting more sleep: 

“You should not actually stay in bed for very long awake, because your brain is this remarkably associative device and it quickly learns that the bed is about being awake. So you should go to another room — a room that's dim. Just read a book — no screens, no phones — and only when you're sleepy return to the bed. And that way your brain relearns the association with your bedroom being about sleep rather than wakefulness.”

Meditation can also be helpful: “It just quiets the mind and it dampens down what we call the ‘fight or flight’ branch of the nervous system, which is one of the key features of insomnia.”

“Sleep is not like the bank, so you can't accumulate a debt and then try and pay it off at a later point in time. And the reason is this: We know that if I were to deprive you of sleep for an entire night — take away eight hours — and then in the subsequent night I give you all of the sleep that you want, however much you wish to consume, you never get back all that you lost. You will sleep longer, but you will never achieve that full eight-hour repayment, as it were. So the brain has no capacity to get back that lost sleep that you've been lumbering it with during the week in terms of a debt.”

“The amount of sleep — the total amount of sleep that you get — starts to decrease the older that we get. I think one of the myths out there is that we simply need less sleep as we age, and that's not true, in fact. We need just as much sleep in our 60s, 70s, 80s, as we do when we're in our 40s. It's simply that the brain is not capable of generating that sleep, which it still needs, and the body still needs. So, total amount of sleep actually decreases.”

“We also know that the continuity of sleep also starts to fall apart. Sleep becomes much more fragmented. There are many more awakenings throughout the night — pain, bathroom trips, etc. But we also know that it's not the quantity of sleep that changes with aging, it's also the quality of sleep. It seems to be particularly the deepest stage of sleep — something that we call non-rapid-eye-movement sleep, or non-REM sleep, the very deepest stages of non-REM sleep — those are selectively eroded by the aging process.”

Walker is the author of "Why We Sleep: Unlocking the Power of Sleep and Dreams." He's a professor of neuroscience and psychology at the University of California, Berkeley and the director of the Sleep and Neuroimaging Laboratory. Previously he was a sleep researcher and professor at Harvard University and the founder of the Center for Human Sleep Science.

He spoke Oct. 26, 2017, at the Commonwealth Club of California. The moderator is Alison van Diggelen of the BBC.