What Sleep Deprivation Really Does to Your Body

Wondering if your nighttime habits are wearing on your wellbeing? Learn the causes, symptoms, and side effects of sleep deprivation to better understand how a lack of shuteye can impact your life.

By Sharon Liao

Published March 8, 2021

A work deadline is looming. Another episode of Bridgerton is calling. Whatever the cause, many of us just don’t get enough sleep. More than one in three Americans clock less than seven hours of shuteye per night, according to a survey published in the journal Sleep.

While an occasional sleepless night may only have a minor effect on how someone feels and functions, chronic sleep deprivation can have a major impact on a person’s health, says sleep specialist W. Chris Winter, MD, author of The Sleep Solution.

Read on as medical experts share the signs and effects of sleep deprivation—plus research-proven tips to help you score a better night’s rest.

What is sleep deprivation?

Sleep deprivation is a condition where you don’t get enough rest—either occasionally or chronically, says Fariha Abassi-Feinberg, MD, a neurologist on the American Academy of Sleep Medicine’s board of directors. Everyone’s “adequate amount” varies: Some people require nine hours of shut-eye a night, while others feel fine with seven, Dr. Abassi-Feinberg says. If you don’t meet your body’s requirement, you are experiencing sleep deprivation—and likely the physical and mental symptoms that tend to come with it (more on those in a sec).

What causes sleep deprivation?

Sleep deprivation can be caused by lifestyle circumstances (including familial demands and work schedules), as well as medical conditions (such as depression, sleep apnea, and hormone imbalances.) Medications, caffeine, and alcohol can also interfere with sleep.

Sometimes, though, many of us simply drop the ball on prioritizing slumber, Dr. Abassi-Feinberg says. “We’re scrolling through social media or watching a show on Netflix,” she says. “Habits like these push back your bedtime, cutting into your rest.”

Symptoms of sleep deprivation

If you feel beat and can’t stop yawning throughout the day, those are telltale signs that you’re not getting enough ZZZs, Dr. Winter says. But fatigue isn’t the only signal that you’re short on sleep. Other possible signs include:

Difficulty remembering things: Can’t find your keys (again)? That late-night scroll may be to blame. The brain processes memories during sleep, Dr. Winter says, so falling short on slumber can affect both short- and long-term memory.
Altered decision making: Don’t be surprised if you regret a choice you made when you were exhausted. Research shows that people are more likely to make risky or poor decisions when they’re sleep deprived.
Trouble regulating emotions: Even one or two nights of tossing and turning can affect your mood, Dr. Abassi-Feinberg says. When you’re sleep deprived, you may have a shorter fuse, and feel crankier, sadder, and more stressed.
Difficulty staying focused: Sleep deprivation decreases activity in the part of the brain that controls attention and alertness, according to a study published in the journal Neuropsychopharmacology.

Physical effects of sleep deprivation

Not getting enough sleep night after night can take a toll on the body. Sleep deprivation may increase a person’s risk of the following conditions:

Weakened immune system: Sleep loss reduces the function of key immune cells. That may be why one study found that people who slept six or fewer hours a night for one week were four times more likely to catch a cold than those who logged more shuteye.
Type 2 diabetes: Sleep deprivation affects the body’s production of and sensitivity to insulin, a hormone that regulates blood sugar levels. A small study of nine healthy adults found that one night of serious sleep deprivation (subjects got just 4 hours of shuteye) was enough to set off insulin resistance, a risk factor for type 2 diabetes.
High blood pressure: People who reported sleeping less than six hours on average a night were 66% more likely to have hypertension than those who snoozed longer, according to a large study published in the journal Sleep.
Heart disease: Not getting enough sleep doesn’t just increase the risk of high blood pressure; it’s correlated with inflammation, as well—and these conditions make a person more likely to develop heart disease.
Stroke: Insufficient sleep triggers processes that may lead to atherosclerosis, fatty buildup in blood vessels that can cause a stroke. Researchers at the University of Alabama at Birmingham found that the risk of stroke was four times greater for people who slept six or fewer hours per night than it was for those who snoozed at least seven hours.

Mental effects of sleep deprivation

Sleep loss affects the way the brain works, Dr. Winter says, which may lead to the following:

A quick temper: Sleep-deprived people react to frustrating situations with more stress and anger. Preliminary research points to a possible connection in gray matter: Sleep deprivation is linked with greater activity in the amygdala, an area of the brain tied to feelings of agitation.
Increased anxiety: Worry and sleep deprivation are intertwined in what scientists call a “bidirectional relationship.” Stressful thoughts can keep you up at night, and research shows that sleep problems can set the stage for anxiety, perpetuating a cycle.
Impaired cognitive performance: Not getting enough shuteye may reduce a person’s attention span, memory, and motivation, according to research published in the journal Neuropsychiatric Disease and Treatment.
Increased sadness and depression: There’s a strong link between sleep issues and depression: One study found that 40% of people with depression have trouble falling and/or staying asleep. Research suggests that sleep deprivation affects brain chemistry and hormones, which may negatively affect a person’s mood.

Can lack of sleep affect your weight?

There’s definitely a connection between slumber and the scale, but it’s not as direct as “sleep more, weigh less.” Sleep loss increases levels of ghrelin, a hormone connected to hunger, while decreasing levels of leptin, a hormone linked to feelings of fullness. This may lead sleep-deprived people to eat more than they would if they were well rested, Dr. Abassi-Feinberg says. Sleep also affects decision making and cravings, which influence eating patterns.

A review of research found that, on average, people eat an extra 384 calories per day when they’re sleep deprived than they do when they’re well rested—without expending more energy. If that happens often enough, it stands to reason that weight gain could result. So while there isn’t a direct correlation between how much you sleep and how much you weigh, it’s clear that shuteye could affect the number on the scale.

Is there a treatment for sleep deprivation?

Let it be said: A third cup of coffee isn’t a cure for sleep loss. The only way to truly combat the effects of sleep deprivation is to get the shuteye your body requires. Seven to nine hours is the go-to recommendation for adults, but that’s a big range. To zero in on your ideal amount, note your bedtime and let yourself wake up naturally without an alarm on a few occasions. “That’s usually the amount of sleep you need,” Dr. Abassi-Feinberg says.

It also helps to ask yourself some key questions: Do you wake up feeling refreshed? Or are you still tired throughout the day, less focused and productive than you’d like? Tracking your responses against your sleep schedule may reveal insights unique to you.

Tips for preventing sleep deprivation

Once you’ve got a sleep goal in mind, the research-based strategies below can help you reach it. But before you dive in, you might want to check in with your doctor first. Sleep deprivation that’s caused by a medical issue—such as depression, sleep apnea, or a prescription medication—may call for an approach beyond lifestyle modifications.

Create a sleep-friendly bedroom: Make your room dark and cool, Dr. Abassi-Feinberg says, since darkness helps trigger production of the hormones that support sleep, and most people snooze better in cooler temps (60–67°F). Remove or dim any light sources, such as clocks and chargers. Also consider your mattress and pillow: If you wake up feeling achy, it might be time to replace them.
Cut back on wine, beer, and cocktails: Although alcohol is a sedative, it actually suppresses the restorative stages of slumber, Dr. Winter says. Research shows that alcohol decreases sleep quality and duration. If you’re going to have a drink, try to cut yourself off at least four hours before bedtime so your body has a chance to metabolize the alcohol before you nod off.
Create a bedtime routine: Doing the same relaxing things each night signals to your brain that it’s time to switch into sleep mode. Try reading a book, taking a shower, or listening to soft music, Dr. Abassi-Feinberg says.
Stick to a set bedtime: Aim to go to bed around the same time every night—yes, even on weekends! Research shows that a consistent bedtime is linked with better sleep and less daytime sleepiness.
Switch off screens: The blue light emitted from phones, tablets, computers, and TVs suppresses melatonin, a hormone important for helping you fall asleep. “Ideally, turn off devices 90 minutes before bedtime,” Dr. Abassi-Feinberg says.
Get active: Walk, bike, dance—whatever gets you moving and grooving—on most days. Research shows doing at least 30 minutes of moderate-intensity activity, five days a week, improves sleep quality and length. If you can get active outdoors, even better: Sunlight helps regulate your internal body clock, Dr. Winter says, which can help you snooze more soundly at night.
Skip the afternoon latte: Although everyone is different, it usually takes about six to eight hours to metabolize caffeine, Dr. Abassi-Feinberg says. Time your last coffee of the day accordingly, or switch to decaf if you don’t want to give up a late-afternoon cup.

The upshot: Adequate sleep is key for good health

Feeling tired and foggy isn’t a normal part of life—it can mean you’re not getting the amount of rest your body needs. Shortchanging sleep can affect a person’s mood and ability to handle stress, Dr. Winter says, and research shows that sleep deprivation may also increase the risk of experiencing certain health issues. The good news: Experts have found that making a few lifestyle changes can often help people get the ZZZs they need. If simple modifications don’t make a difference, check in with your doctor or a sleep specialist to explore other medical issues that may be involved.

Sharon Liao is a freelance writer and editor specializing in health, nutrition, and fitness. She lives in Redondo Beach, California.

This article was reviewed for accuracy in July 2021 by Stephanie L. Fitzpatrick, PhD, senior manager for multicultural programs at WeightWatchers®. The WW Science Team is a dedicated group of experts who ensure all our solutions are rooted in the best possible research.