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About a third of US adults don’t get enough sleep.
Unfortunately, sleep deprivation has serious consequences for your brain and body.
Many people think they can get by on less than seven to nine hours per night — the amount of sleep doctors recommend for most adults — or say they need to sleep less because of work or family obligations.
Tesla and SpaceX CEO Elon Musk recently acknowledged in an interview with the New York Times that his long work hours are taking a toll on his well-being and raising concerns among his friends.
That prompted Ariana Huffington to post an open letter to Musk about his sleep schedule, telling him that he was “demonstrating a wildly outdated, anti-scientific and horribly inefficient way of using human energy.”
Musk posted his response on Twitter at 2:30 a.m.: “I just got home from the factory. You think this is an option. It is not.”
Musk seems to understand that working 120-hour weeks is harmful. As sleep expert and neuroscientist Matthew Walker previously told Business Insider, “the shorter your sleep, the shorter your life.”
The vast majority of adults need seven to nine hours of nightly sleep, and kids have to get even more, though needs do vary from person to person. Some incredibly rare people can actually get by on a few hours of sleep per night, while others on the opposite end of the spectrum are sometimes called “long sleepers” because they need 11 hours nightly.
But regardless of your body’s clock, a lack of sleep will cause your physical and mental health to suffer.
Here are 30 health consequences of sleep deprivation.
Sleep deprivation is linked to higher risk for certain cancers.
Sleep deprivation and a disrupted sleep schedules have been linked to increased risk for a number of cancers, most notably colon and breast cancers.
Skin doesn’t heal as well from damage when you are tired, leading to skin aging.
Poor sleep quality is strongly correlated to chronic skin problems, according to research from the University of Wisconsin. Studies have also shown that when skin is damaged by the sun or other factors, it doesn’t heal as well in poor sleepers, so those people wind up showing more signs of skin aging.
Tired people have a harder time controlling their impulses, which leads to unhealthy behavior and weight gain.
People who don’t get enough sleep have a harder time resisting high-calorie foods, more cravings for unhealthy meals, and difficulty controlling their impulses. Researchers think hormonal imbalances that result from sleep deprivation are responsible for this, since those imbalances are linked to a high body mass index and obesity.
People feel more lonely after sleepless nights — and being lonely makes it harder to sleep well.
Etienne Oliveau/Getty Images
Researchers have found that sleep-deprived young adults are less likely to connect socially with other people, and that people who report poor sleep also tend to say they’re more lonely. To make things worse, people who feel lonely don’t tend to sleep as well, which can lead to a sort of vicious cycle.
Being sleepy makes it harder to learn and disrupts short-term memory.
Sleepiness has long been a problem for students. Delaying school start times an hour for middle school kids significantly increases standardized test scores, and research shows this has an even bigger effect on teens, who naturally tend to be night owls.
But it’s not just kids — sleep deprivation also wrecks adults’ short-term memory. Several studies have shown that sleep-deprived adults have more difficulty remembering words they’ve learned and have a harder time improving at newly learned skills.
A growing body of evidence links bad sleep with signs of Alzheimer’s in the brain.
Neural connections in the brainNIH
Several studies have shown that sleep helps cleanse the brain of the beta-amyloid protein that can build up while you are awake. That protein is strongly associated with Alzheimer’s disease. Researchers say that a lack of sleep can lead to a vicious cycle, since the more beta-amyloid there is in the brain, the harder it is to get to a cleansing deep-sleep state. People with more disrupted sleep schedules tend to have more beta-amyloid built up.
The longer people go without sleep, the harder it is for them to see clearly. People sometimes experience hallucinations when sleep deprived.
Sleep deprivation is associated with tunnel vision, double vision, and perceived dimness. The longer you are awake, the more visual errors you’ll encounter, and the more likely you are to experience outright hallucinations.
Sleep-deprived people have slower reactions.
Your reaction time is severely impeded when you don’t get enough sleep. Studies have shown that college athletes and West Point cadets all did worse on decision-making tests and had slower reactions while tired.
Similarly, over-tired people are more susceptible to colds.
If you’re wondering why you’re sick all the time and seem to pick up every bug that travels around the office, it’s probably because you’re not getting enough sleep. Sleep-deprived people are almost three times as likely as well-rested people to catch a cold, according to one study.
Sleepy people express more unhappiness and signs of depression.
In a classic study led by Nobel Prize-winning psychologist Daniel Kahneman, a group of 909 working women kept detailed logs of their moods and day-to-day activities. While differences in income up to $60,000 had little effect on happiness, the results showed, a poor night’s sleep was one of two factors that could ruin the following day’s mood. (The other was tight deadlines at work.)
Another study reported higher marital happiness among women with more peaceful sleep, although it’s hard to say whether happy people sleep better or good sleep makes people happier. Most likely, it’s some combination of the two.
Insomniacs are also twice as likely to develop depression, and research suggests that treating sleep problems may help successfully treat depressive symptoms.
Risk of Type 2 diabetes rises when people are over-tired, even for non-overweight people.
Being awake when your body wants you to be asleep messes with your metabolism, which in turn increases your risk for insulin resistance (often called “pre-diabetes”) and type 2 diabetes.
A number of studies in adults have found a strong association — though not a cause-effect relationship — between regular sleep loss and the risk of developing diabetes. More sleep may also help reduce diabetes risk for adolescents, according to researchers.
Tiredness is associated with bad decision-making that puts lives and finances in danger.
Planning to make some changes to your portfolio? You might want to make sure you’re well rested.
“A single night of sleep deprivation evoked a strategy shift during risky decision making such that healthy human volunteers moved from defending against losses to seeking increased gains,” researchers concluded.
Other researchers have found that severe sleep deprivation impairs people’s ability to follow pre-established procedures for making a “go” or “no-go” decision, something that researchers say contributed to the space shuttle Challenger explosion, the Chernobyl meltdown, and the Exxon Valdez disaster.
Sleepy people are more easily distracted.
“Attention tasks appear to be particularly sensitive to sleep loss,” researchers have noted.
If you want to stay alert and attentive, sleep is a requirement. Otherwise, you enter “an unstable state that fluctuates within seconds and that cannot be characterized as either fully awake or asleep.” In that state, your ability to pay attention is variable at best.
Tiredness makes it hard to speak normally.
Severe sleep deprivation seems to affect your ability to carry on a conversation — much like having too much to drink.
“Volunteers kept awake for 36 hours showed a tendency to use word repetitions and clichés; they spoke monotonously, slowly, [and] indistinctly,” one study noted. “They were not able to properly express and verbalize their thoughts.”
Driving tired leads to more car accidents, like driving drunk.
Drowsy driving is often compared to drunk driving: You really shouldn’t do either.
“Motor vehicle accidents related to fatigue, drowsy driving, and falling asleep at the wheel are particularly common, but often underestimated,” one review concluded. Pilots, truck drivers, medical residents, and others required to stay awake for long periods of time “show an increased risk of crashes or near misses due to sleep deprivation,” it said.
Tiredness is connected to urine overproduction.
When people sleep, the body slows down its normal urine production. But when someone is sleep deprived, this normal slowdown doesn’t happen, leading to what researchers call “excess nocturnal urine production.”
This condition may be linked to bed wetting in children. In adults, it’s tied to what’s called nocturia — the need to use the bathroom many times during the night.
You need sleep for muscles to get stronger. Without it, muscle atrophy occurs.
Lack of sleep causes hormonal changes that make it harder for your body to build muscle and heal. This makes it more difficult to recover from muscle damage caused by exercise, and it worsens conditions related to muscle atrophy.
Other research has shown that the reverse is also true — during sleep, your body releases growth hormone and heals damage. That’s fitness advocates will always point out that sleep is an essential part of getting into shape.
Sleepiness makes pain harder to cope with.
People in pain — especially those suffering from chronic pain — tend not to get enough sleep. This makes sense, since pain can wake you up in the night and make it hard to fall asleep in the first place. But recently, researchers have begun to suspect that sleep deprivation may actually cause pain or at least increase people’s sensitivity to pain.
Tiredness leads to gastrointestinal issues.
Regular sleep loss makes you more likely to develop both Inflammatory Bowel Disease (IBD) and inflammatory bowel syndrome, which affects an estimated 10-15% of people in the US. Patients with Crohn’s disease have been shown to be twice as likely to experience a relapse when they don’t get enough sleep.
Disrupted sleep cycles lead to more inflammation, which could worsen asthma, arthritis, and cardiovascular disease.
Our sleep cycle or body clock doesn’t just determine when we’re tired or awake; it also affects the function of every cell in our body. Researchers have started to figure out how disruptions in sleep schedules prevent cells from fighting inflammation, which could explain why tired people suffer so many problems from inflammatory conditions including asthma, arthritis, multiple sclerosis, and cardiovascular disease.
Poor sleep disrupts genetic activity, which may explain some of the health risks of getting too little rest.
Dragan Radovanovic/Business Insider
A 2013 study shed some light on why sleep is tied to so many different aspects of our health and wellness. Poor sleep actually disrupts normal genetic activity. After study participants slept less than six hours per night for a week, researchers found that more than 700 of their genes were not behaving normally, including some that help govern immune and stress responses.
Some genes that typically cycle according to a daily (circadian) pattern stopped doing so, while others that don’t normally follow a daily pattern began doing so. What does this mean? Just one week of less-than-ideal sleep is enough to make some of your genetic activity go haywire.
At any given time, people who haven’t gotten the right amount of sleep are more likely to die.
Many health problems are associated with sleep deprivation and poor sleep, but here’s the big one: People who consistently do not get 7 or 8 hours of sleep per night are more likely to die during a given time period. Put more simply: We all die eventually, but sleeping too little — or even too much — is associated with a higher risk of dying sooner than you would otherwise.
Lauren Friedman wrote an earlier version of this story.
