Sleep plays a vital role in good health and well-being throughout your life. Getting enough quality sleep at the right times can help protect your mental health, physical health, quality of life, and safety.

The way you feel while you’re awake depends in part on what happens while you’re sleeping. During sleep, your body is working to support healthy brain function and maintain your physical health. In children and teens, sleep also helps support growth and development.

The damage from sleep deficiency can occur in an instant (such as a car crash), or it can harm you over time. For example, ongoing sleep deficiency can raise your risk for some chronic health problems. It also can affect how well you think, react, work, learn, and get along with others.

Healthy Brain Function and Emotional Well-Being

Sleep helps your brain work properly. While you’re sleeping, your brain is preparing for the next day. It’s forming new pathways to help you learn and remember information.

Studies show that a good night’s sleep improves learning. Whether you’re learning math, how to play the piano, how to perfect your golf swing, or how to drive a car, sleep helps enhance your learning and problem-solving skills. Sleep also helps you pay attention, make decisions, and be creative.

Studies also show that sleep deficiency alters activity in some parts of the brain. If you’re sleep deficient, you may have trouble making decisions, solving problems, controlling your emotions and behavior, and coping with change. Sleep deficiency also has been linked to depression, suicide, and risk-taking behavior.

Children and teens who are sleep deficient may have problems getting along with others. They may feel angry and impulsive, have mood swings, feel sad or depressed, or lack motivation. They also may have problems paying attention, and they may get lower grades and feel stressed.

Physical Health

Sleep plays an important role in your physical health. For example, sleep is involved in healing and repair of your heart and blood vessels. Ongoing sleep deficiency is linked to an increased risk of heart disease, kidney disease, high blood pressure, diabetes, and stroke.

Sleep deficiency also increases the risk of obesity. For example, one study of teenagers showed that with each hour of sleep lost, the odds of becoming obese went up. Sleep deficiency increases the risk of obesity in other age groups as well.

Sleep helps maintain a healthy balance of the hormones that make you feel hungry (ghrelin) or full (leptin). When you don’t get enough sleep, your level of ghrelin goes up and your level of leptin goes down. This makes you feel hungrier than when you’re well-rested.

Sleep also affects how your body reacts to insulin, the hormone that controls your blood glucose (sugar) level. Sleep deficiency results in a higher than normal blood sugar level, which may increase your risk for diabetes.

Sleep also supports healthy growth and development. Deep sleep triggers the body to release the hormone that promotes normal growth in children and teens. This hormone also boosts muscle mass and helps repair cells and tissues in children, teens, and adults. Sleep also plays a role in puberty and fertility.

Your immune system relies on sleep to stay healthy. This system defends your body against foreign or harmful substances. Ongoing sleep deficiency can change the way in which your immune system responds. For example, if you’re sleep deficient, you may have trouble fighting common infections.

Daytime Performance and Safety

Getting enough quality sleep at the right times helps you function well throughout the day. People who are sleep deficient are less productive at work and school. They take longer to finish tasks, have a slower reaction time, and make more mistakes.

After several nights of losing sleep—even a loss of just 1–2 hours per night—your ability to function suffers as if you haven’t slept at all for a day or two.

Lack of sleep also may lead to micro-sleep. Micro-sleep refers to brief moments of sleep that occur when you’re normally awake.

You can’t control micro-sleep, and you might not be aware of it. For example, have you ever driven somewhere and then not remembered part of the trip? If so, you may have experienced micro-sleep.

Even if you’re not driving, microsleep can affect how you function. If you’re listening to a lecture, for example, you might miss some of the information or feel like you don’t understand the point. In reality, though, you may have slept through part of the lecture and not been aware of it.

Some people aren’t aware of the risks of sleep deficiency. In fact, they may not even realize that they’re sleep deficient. Even with limited or poor-quality sleep, they may still think that they can function well.

For example, drowsy drivers may feel capable of driving. Yet, studies show that sleep deficiency harms your driving ability as much as, or more than, being drunk. It’s estimated that driver sleepiness is a factor in about 100,000 car accidents each year, resulting in about 1,500 deaths.

Drivers aren’t the only ones affected by sleep deficiency. It can affect people in all lines of work, including health care workers, pilots, students, lawyers, mechanics, and assembly line workers.

As a result, sleep deficiency is not only harmful on a personal level, but it also can cause large-scale damage. For example, sleep deficiency has played a role in human errors linked to tragic accidents, such as nuclear reactor meltdowns, grounding of large ships, and aviation accidents.

How to Discuss Sleep With Your Doctor

Doctors might not detect sleep problems during routine office visits because patients are awake. Thus, you should let your doctor know if you think you might have a sleep problem.

For example, talk with your doctor if you often feel sleepy during the day, don’t wake up feeling refreshed and alert, or are having trouble adapting to shift work.

To get a better sense of your sleep problem, your doctor will ask you about your sleep habits. Before you see the doctor, think about how to describe your problems, including:

  • How often you have trouble sleeping and how long you’ve had the problem
  • When you go to bed and get up on workdays and days off
  • How long it takes you to fall asleep, how often you wake up at night, and how long it takes you to fall back asleep
  • Whether you snore loudly and often or wake up gasping or feeling out of breath
  • How refreshed you feel when you wake up, and how tired you feel during the day
  • How often you doze off or have trouble staying awake during routine tasks, especially driving

Your doctor also may ask questions about your personal routine and habits. For example, he or she may ask about your work and exercise routines. Your doctor also may ask whether you use caffeine, tobacco, alcohol, or any medicines (including over-the-counter medicines).

To help your doctor, consider keeping a sleep diary for a couple of weeks. Write down when you go to sleep, wake up, and take naps. (For example, you might note: Went to bed at 10 a.m.; woke up at 3 a.m. and couldn’t fall back asleep; napped after work for 2 hours.)

Also write down how much you sleep each night, how alert and rested you feel in the morning, as well as how sleepy you feel at various times during the day. Share the information in your sleep diary with your doctor. You can find a sample sleep diary in the National Heart, Lung, and Blood Institute’s “Your Guide to Healthy Sleep.”

Doctors can diagnose some sleep disorders by asking questions about sleep schedules and habits and by getting information from sleep partners or parents. To diagnose other sleep disorders, doctors also use the results from sleep studies and other medical tests.

Sleep studies allow your doctor to measure how much and how well you sleep. They also help show whether you have sleep problems and how severe they are. For more information, go to the Health Topics Sleep Studies article.

Your doctor will do a physical exam to rule out other medical problems that might interfere with sleep. You may need blood tests to check for thyroid problems or other conditions that can cause sleep problems.

For more information, visit the National Heart, Lung and Blood Institute website:

https://www.nhlbi.nih.gov/health/health-topics/topics/sdd/why