11 Surprising Things That Happen To Your Body When You Don’t Get Enough Sleep

You may notice that you move at a slower pace, both mentally and physically, when you haven’t slept much, and your cognitive performance will probably suffer, too. “A well-rested brain results in a person with improved learning and a better attention span,” Dr. Lynelle Schneeberg, PsyD, a board-certified sleep psychologist at Yale, tells Bustle. “The brain lays down new pathways that help us learn new things and help us categorize and remember what we’ve already learned during sleep.”

Alex Dimitriu, MD, founder of Menlo Park Psychiatry & Sleep Medicine, agrees. “A lack of sleep can affect your attention, focus, and memory,” he tells Bustle. “Your brain needs sleep to archive information you learned, and make room for new things. I see a lot of young people in their 20s and 30s reporting ADHD symptoms, or ‘early-onset Alzheimer’s,’ when the reality is they are sleep-deprived.”

In the Reverie study, 41 percent of people felt their stress level influences their sleep quality most. “While diet and exercise are often viewed as the components for leading a healthy lifestyle, sleep is an essential third pillar,” Dr. Sujay Kansagra, Mattress Firm’s sleep health expert, tells Bustle. “Unfortunately, sleep is not optional, and getting limited quantities has real consequences, as it helps our bodies recover from a stressful day and prepare for the morning ahead.

If you feel you get sick a lot, it could be because you don’t sleep enough. “A lack of sleep lowers immunity,” Dr. Dimitriu says. “Sleep-deprived people tend to get sick more easily and stay sick longer.”

After a night of tossing and turning, you may be more irritable and moody, which is another side effect of not getting enough sleep. “If a person has obtained adequate sleep, [they] will feel alert and in a good mood shortly after arising,” Dr. Schneeberg says.

“If you get one or two hours less sleep than you want, your brain doesn’t refresh its ability to manage load fully, ”Dr. Smarr says. “This manifests in slower reaction times, less attention, and also less emotional control. One of the reasons teenagers can be so moody is that their biological clocks shift later when puberty hits, but their school day doesn’t.” He says that the result is kids getting woken up before their bodies have had the time they expected for sleeping, and this damages their emotional resilience.

You may experience increased inflammation if you’re not sleeping enough. “Many people with autoimmune diseases may be aware that inflammatory conditions, like eczema, can often get worse with stress and sleep deprivation,” Dr. Dimitriu says.

You may notice that when you don’t sleep enough, you have problems focusing the next day. Dr. Schneeberg says that a lack of sleep is to blame. “Complex tasks are much more difficult — no one wants a sleep-deprived physician or surgeon or pilot and so on,” she says.

You already may feel more moody and irritable from not sleeping much, but lack of sleep can aggravate depression, too. “Your emotional systems need sleep to be well calibrated,” Dr. Dimitriu says. “The fatigue from sleep deprivation can easily make someone look and feel depressed — with little interest in doing things, and no energy to do it.”

Dr. Dimitriu adds that anxiety erupts from a feeling of being overwhelmed. “A lot of my sleep-deprived patients alternate between feeling half asleep, or sharply, anxiously awake, in response to some perceived emergency or threat,” he says. “This tends to become a cycle of fatigue and anxiety.”

If you’re overtired, you may drink a ton of coffee, but some people choose to use other substances, too, to stay awake. “Dragging through all the challenges of a day with insufficient sleep leaves people exhausted and worn out,” Dr. Dimitriu says. As a result, many people will turn to substance use — alcohol or other drugs — to calm these feelings, he says. “But part of the actual problem is the lack of sleep in the first place — it really tends to make life hard when it doesn’t necessarily have to be.”

You may have heard that driving when sleep-deprived is as dangerous as driving drunk, and studies back up this theory. For example, a study from AAA found that driving while tired was a factor in 20 percent of fatal crashes. For instance, people who sleep less than four hours within 24 hours and 11.5 times more likely to crash. However, even missing a few hours still influences your driving: If you miss one or two hours of sleep out of seven, your crash risk doubles. “Not getting enough sleep is extremely dangerous for drivers,” Robert Sinclair Jr., manager of media relations for AAA Northeast, told U.S News & World Report. “Our new research shows that getting less than five hours sleep is the same as driving drunk.”

Dr. Smarr agrees. “After a single night of sleep deprivation, your reaction time and alertness are equivalent to being at the legal limit of alcohol consumption,” he says. “However, because you don’t feel drunk after a poor night’s sleep, this can give a false sense of confidence or safety."

In case you weren’t aware, a lack of sleep can also impact your sex life. “The benefits of sleep are widely known, and one benefit of sleep that many don’t consider is improved sexual functioning,” Dr. Rachel Needle, licensed psychologist and certified sex therapist in West Palm Beach, FL, and the co-director of Modern Sex Therapy Institutes, tells Bustle. “Less sleep can impact hormone levels, which leads to a worse mood and decrease in motivation and energy — all of which can in turn lead to lower sexual desire and arousal.”

As you can see, there are many negative side effects of not getting enough sleep that you probably never realized.

“Convincing people of the value of sleep can be challenging, because we often don’t feel the effects as poignantly as, say, a lack of food,” he says. “Sleep is more like love — everybody feels good when they get it, but day-to-day, it’s easy to ignore (or get used to) its absence. Over a lifetime though, people without love — meaning friends, family, and community, not just romance — get more diseases and die younger, on average.”

He adds that when you don’t get enough good sleep, you don’t feel pain right away, but all the parts of your brain and body that depend on that sleep now have to go without. So, in essence, this makes your body’s jobs harder, and puts more wear on you overall. “Getting good sleep can keep you healthy longer, so invest in sleep,” Dr. Smarr says. No doubt about it — there's certainly plenty of incentive to try and get more sleep.