Who doesn’t love to sleep? The trouble is that some of us don’t do it very well, but perhaps that can be improved with a better understanding of sleep through evolution.
If you’re lucky, you’ll spend a third of your life asleep. “That’s pretty incredible if you think about it, because when we’re asleep we’re not doing things that are important for our survival or reproductive success,” says Charles Nunn, a professor of evolutionary anthropology at Duke University.
“We’re not searching for food, watching for predators, raising offspring, or searching for mates,” he told attendees at the International Society for Evolution, Medicine, and Public Health Inaugural Meeting on March 20, 2015 in Tempe, Ariz.
But nearly all animals show some signs of sleep. The birds do it, the bees do it, jellyfish, and fruit flies all sleep too. We know there are complex neurophysiological mechanisms going on during sleep. And we know that if we don’t get enough, our mental and physical health suffers, as is most clearly exemplified by the more than 70 million Americans who suffer from a sleep disorders.
When humans go to sleep, they first go into the lighter stages non-REM sleep, followed by the deeper stages (slow-wave sleep), then arouse out briefly, and go into REM sleep, where dreams come, arouse briefly again, and then the cycle continues. Each of these cycles lasts about 90 minutes to two hours, and is repeated, for around eight hours in humans.
But why has sleep evolved? More importantly, what is the evolutionary context of which human sleep has evolved? By researching these questions, Nunn says, it might just help us to better understand sleep disorders such as insomnia, narcolepsy, seasonal affective disorder, and circadian rhythm disorders. Continue reading “Why we sleep the way we do”
Evolving Health 
