In our overscheduled, device-dominated lives, it's too easy to consider sleep a waste of time. And in fact, Americans are getting less shut-eye than ever before: According to Gallup, the average American sleeps only 6.8 hours per night, compared to nine hours in the early twentieth century. When everyone's logging fewer hours, it's easy to lose sight of why sleep is important.
So why is sleep important? Science has linked insufficient sleep to a number of ailments, including depression, weight gain, ADHD, heart disease, cancer and Alzheimer's Disease. It's no wonder that in 2014 the Center for Disease Control named inadequate sleep a "public health epidemic." The National Sleep Foundation recommends that the average adult get 7 to 9 hours each night, and warns that fewer than 6 can be problematic.
So put down your cellphone, start DVR'ing Seth Meyers and hit the hay at a decent hour! Poor sleep hygiene — mainly, staring at screens and eating too close to bedtime — is a major contributor to insomnia. Need more convincing? Here are the top reasons why sleep is important (that you may not already know).
Why sleep is important
1. Sleep helps you stay a healthy weight
Numerous studies have shown that inadequate sleep can contribute to significant weight gain. Why? According to the director of the Sleep, Metabolism and Health Center at the University of Chicago, sleep deprivation increases ghrelin, known as "the hunger hormone," and decreases leptin, the hormone that regulates satiety, leading to overeating. People who undersleep consume about 300 more calories per day than someone who's well-rested, and their bodies respond less efficiently to insulin, which regulates how the body uses calories for energy. Sleeping with a partner also lowers levels of the stress hormone cortisol; at elevated levels, it tells the body to hang on to belly fat.
2. Sleep boosts your mental health
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A lack of sleep has been linked to depression and Alzheimer's Disease. Research shows that people with insomnia have ten times the risk of developing depression than those who sleep soundly. What's more, a 2017 study published in the journal Neurology showed that sleeplessness can interfere with the brain's "glymphatic system," a cleaning procedure that happens during sleep, in which cerebrospinal fluid flushes waste from the spaces between neurons. A buildup of that waste, or plaque, has been linked to dementia and Alzheimer's.
3. Sleep protects against cancer and heart disease
The "body clock" isn't just a cute concept — sleep keeps your inner machinery running properly. During sleep, our body produces the hormone melatonin — which only happens during sleep and at night. Several studies have shown that people who have lower levels of melatonin (such as night-shift workers) have a higher incidence of several cancers. And because insomniacs have trouble processing insulin as mentioned above, they run the risk of developing "metabolic syndrome," which raises the chance of weight gain, diabetes and cancer.
4. Sleep improves your sex life
If all that wasn't enough to convince you, here's perhaps a more compelling reason why sleep is important: Sleep is crucial to the production of testosterone, which is key to both the male and female libido. Studies have shown that men who sleep four hours a night have roughly half the testosterone level of men who sleep eight hours. Beyond sex, getting adequate sleep might save your relationship — couples who sleep together in bed exhibit higher levels of oxytocin, known as the "bonding hormone."