Sleep. It’s one of the three pillars of health—along with exercise and diet—that we crave to get more of. Yet when it comes to priorities, we seem to constantly shortchange getting our z’s. When we do finally pay attention, some find that sleep doesn’t come as easily as we would like it to. Like any relationship in life, it’s one that needs nurturing.  

All About Sleep Cycles 

Why is sleep so important? The first thing to know is that when we sleep, our brains don’t. Parts of the brain are in fact very active, even more so than while we are awake. “Sleep is not a uniform state. Sleep is an umbrella term for the cycles of stages of sleep that occur throughout the night,” says Michael Scullin, Ph.D., director of the Sleep Neuroscience and Cognition Laboratory at Baylor University. 

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To get a good night’s sleep, we cycle through stages. The first four are non-REM (rapid eye movement) sleep. The first two of these are quite light, lulling us into deeper sleep. If you were to take a nap, ideally you would take one for 30 minutes and wake up before you hit stage three of non-REM sleep. Stages three and four take you into deeper, more restorative sleep. This is when your body gets to work repairing muscles and tissues, boosting your immune function, building up energy and, in kids and teenagers, stimulating growth and development.

The final stage of the sleep cycle is REM sleep. This is when you dream. It’s also when your brain gets more active and memories consolidate, as your brain processes information from the day. It’s in this stage that your brain decides what to discard and what to store as memory. More recently, this phase has also been associated with clearing our brains of metabolites, a buildup of which has recently been associated with Alzheimer’s, says Scullin. 

“During the day, our brain engine is running, and as an engine runs it gives off exhaust and needs maintenance. Non-REM sleep is important to that maintenance. As neurons fire during the day, we put off metabolites, but if left unchecked, they can make us really ill,” explains Scullin. 

Alzheimer’s isn’t the only possible health consequence of poor sleep. People who don’t sleep enough put themselves at risk for high blood pressure, diabetes, heart disease, obesity and diminished cognitive function. Not to mention sleep deprivation, which can speed up the aging process, shortening our lives. In fact, if we didn’t sleep,  we would ultimately die. 

There’s a lot to this sleep thing. Although it has often been in vogue to brag about how little sleep you could survive on, the reality is not enough sleep can take an immense toll on your health. You think this would be enough to get us to bed, but still the Centers for Disease Control and Prevention reports that we are experiencing a sleep crisis, with one-third of U.S. adults getting less than the recommended seven hours of sleep per night. Sleep experts recommend on average that adults get between seven to nine hours each night. Our adherence to this affects our creativity, emotional control and ability to learn, among other things.

One of the problems, says sleep expert Mathias Basner, M.D., Ph.D., an associate professor at the University of Pennsylvania Division of Sleep and Chronobiology, is that our bodies adjust to sleep deprivation and even feeling bad. “We habituate to feeling sleepy,” he says. “It becomes the new normal, and that could be one reason our society is chronically sleep-depriving itself. We don’t know how well we could feel if we did sleep.” 

The good news: Regardless of how you’ve shunned sleep in the past, you can benefit from embracing sleep now.

“What if I said today is the first day you had ever heard that aerobic exercise is good for you, and you have this opportunity to engage beginning today in aerobic exercise? It’s the same with sleep. Just because we only recently discovered how important it is across our life span, it doesn’t mean we can’t change things moving forward and benefit from it.”

Time to get sleeping.