'Getting a good night's sleep is possibly the single most important thing you can do every day,' says expert
In new documentary How to Get More Sleep, scientists explain why we need sleep and how to get more of it
We've known why animals eat, drink and reproduce for thousands of years. But why do we, and pretty much all animals on the planet, sleep? "I find it fascinating, because every animal sleeps — every animal that we've studied — from worms to jellyfish to sea slugs," says Gina Poe, a professor at the University of California, Los Angeles, who studies sleep.
In The Passionate Eye documentary How to Get More Sleep, scientists unlock the secrets of an often misunderstood bodily function, explaining why we sleep, why it matters and how we can get more of it. Here are five facts we learned about sleep.
Not all animals sleep the same way
From mammals to slugs to octopi, animals need sleep to function. But how and how much they sleep can vary widely.
"Animals that are vulnerable when they sleep don't sleep very much," says Jerome Siegel, a neuroscientist at the University of California, Los Angeles. "If animals live in the open, they obviously have to be alert and they can't sleep as deeply." In the wild, giraffes often sleep standing up in short bursts, for minutes at a time, totalling no more than four or five hours hours a day. They have among the shortest sleep of mammals partly because they are so exposed to predation on the African savanna. One of the world champions of animal slumber is the brown bat, which can sleep 20 hours straight safely tucked away on a cave wall.
Sleep is crucial to memory
When we're in the deepest phase of sleep, our brain starts to produce what's called delta waves: long, slow brain waves. One of the things that happens in slow-wave sleep is new information, which is stored in the brain's hippocampus, gets moved to the cortex. Rebecca Spencer, who studies sleep at the University of Massachusetts Amherst, says the hippocampus is a short-term storage system. New information gets jammed in there, but there's no real way of organizing it.
"At the end of the day, I can take that information and turn around to my whole, huge filing cabinet, which in this case is the cortex," says Spencer. "It's bigger, and it has a really nice sorting mechanism. You can sort things by their visual components, by their auditory components. That memory becomes easier to find."
Slow-wave sleep may be boosted with the help of pink noise
It's common for older people to have weaker slow brain waves when they sleep, which may be part of the reason memory often gets worse with age.
But in How to Get More Sleep, we watch as Dr. Phyllis Zee of Northwestern University plays short bursts of pink noise for an older patient, strengthening her slow waves. Often found in nature, pink noise consists of all frequencies we can hear, but is more intense at lower frequencies, creating a deep sound. Pink noise is believed to give brain waves a little push, like a kid on a swing or the movement of a ball in a balance pendulum.
"It's beautiful," says Dr. Zee. "This is what we want them all to look like — these very large, with strong upstate, waves. Even after you stopped stimulating, you can see the increase in these slow waves."
10 per cent of people in North America suffer from chronic insomnia
According to scientists, insomniacs suffer from an overactive amygdala, the part of the brain that regulates emotional response. The result is restless REM sleep, when dreams are most vivid. Insomniacs, collectively, spend billions of dollars a year trying to get some sleep in the form of therapy or pills, for example.
Drew Ackerman, who had insomnia as a child, has found a different method. On his podcast Sleep With Me, he tells a boring, meandering story in a dull but soothing voice, trying to help people drift off. "It gives people permission not to listen or to only kind of listen," he says. "I want no social pressure on the listener to pay attention to me at all."
Sleep With Me averages roughly three million downloads a month.
We need to start valuing sleep
Part of the reason people struggle to sleep is cultural, according to Matthew Walker, a sleep scientist at the University of California, Berkeley.
"Somewhere between infancy and even childhood, we — in western industrialized nations — we start to abandon the notion that sleep is useful and, if anything, take the opposite approach and believe that sleep should be shortchanged," he says.
"What we're fast learning is that sleep isn't a luxury. Sleep is a biological necessity."
Adds David Dinges, associate director of the Center for Sleep and Circadian Neurobiology at the University of Pennsylvania, "Getting a good night's sleep is possibly the single most important thing you can do every day."
Watch How to Get More Sleep.