We can all name the benefits of sleep, but saying what sleep accomplishes is a far cry from identifying what sleep is meant to do. The distinction is important. If the point of sleep is that being inactive frees up our energy for other tasks (say, recovering from a cold), we might expect lying in bed with our eyes closed – what some studies call “quiet wakefulness” – to accomplish much the same thing.
Researchers are growing increasingly confident, though, that sleep evolved specifically to recharge the brain. Dr. Chiara Cirelli, a neuroscientist at the University of Wisconsin, has been studying the difference between sleep and quiet wake in humans. She says that while we’re awake, all of our neurons are constantly firing, but that when we’re asleep, the neurons revert to an “up-and-down” state in which only some are active at a given time. During some stages of sleep, all neuron activity goes silent. And that’s likely when the restful part of sleep takes place.
[…] it’s not until we get access to real, deep sleep that we get a cognitive boost from rest. In other studies, test subjects who were made to identify letters flashed on a screen for several hundred milliseconds at a time generally did worse at the exam over the course of a day. Those who got to take a nap halfway through showed more cognitive recovery than those who simply rested quietly, suggesting that there’s a unique benefit to sleep that you don’t get with quiet wakefulness, microsleep, or unihemispheric sleep.
Lying down isn’t completely useless – it does help your muscles and other organs relax. But you’d get the same results just from reclining on the couch. So sleep is still your best friend.
The useful takeaway is that your best move, if you’ve been in bed for 20 minutes and still aren’t dozing off, is to get up and engage in a low-light, low-stress activity like reading until you begin to feel tired. Taking your mind off of “Why am I not sleeping?! I need to sleep!” is crucial. When you do get up, though, don’t use your computer or phone or watch TV – the blue-colored light from the screens tricks your body into thinking it’s daytime and not releasing melatonin. Sweet, sweet melatonin.