Jay Summer is a health content writer and editor. She holds a B.S. in psychology and master's degrees in writing and public policy.
Like eating nutritious food, drinking water, and exercising regularly, getting quality sleep is an important component of overall health. Although the exact reasons humans need to sleep remain unknown, sleep experts agree there are numerous benefits to consistently getting a full night’s rest. Most adults should get between seven and nine hours of sleep each night.
While sleeping, the body performs a number of repairing and maintaining processes that affect nearly every part of the body. As a result, a good night’s sleep, or a lack of sleep, can impact the body both mentally and physically.
Sleep restores the body and improves energy levels, so waking up well-rested can have a positive impact on an individual’s mood. In contrast, people who get inadequate sleep are at higher risk of experiencing mental distress. A chronic lack of sleep can lead to anxiety, depression, and irritability. However, developing a consistent sleep routine often resolves these symptoms.
Quality sleep promotes cardiac health. During sleep, heart rate slows down, and blood pressure decreases. This means that during sleep, the heart and vascular system are able to rest.
However, insufficient sleep is a risk factor for unwanted cardiovascular events. Lack of sleep causes blood pressure to remain high for an extended period of time, increasing the risk of heart disease, heart attack, and heart failure.
Sleep impacts the body’s relationship with the hormone insulin, which helps blood sugar, or glucose, enter the body’s cells. The cells then use glucose as energy. Sleeping seven hours or more each night helps ensure blood sugar is regulated in the body.
Adults who get less than seven hours of sleep at night are at increased risk for Type 2 diabetes. Without enough sleep, the body’s resistance to insulin increases because cells are not able to use insulin appropriately, which leads to too much sugar in the bloodstream.
Sleep is believed to help with memory and cognitive thinking. Brain plasticity theory, a major theory on why humans sleep, posits that sleep is necessary so the brain can grow, reorganize, restructure, and make new neural connections.
Updating these connections in the brain during sleep helps individuals learn new information and form memories. Quality sleep leads to improved concentration and better problem-solving and decision-making skills. In other words, a good night’s sleep can increase productivity.
A lack of sleep can have a negative impact on the ability to think clearly, form memories, learn well, and function optimally during the day. The ability to think quickly slows down after only a week of insufficient sleep. Accuracy on tasks also decreases after a week of getting five hours of sleep or less each night. Sleep-deprived people perform poorly in activities that require quick responses and attention to multiple tasks, such as driving.
Insufficient sleep also impacts judgment. Less than five hours of sleep at night is correlated with riskier behavior. A sleep-deprived person is at higher risk of making poor decisions because they only have the ability to focus on a desired outcome, not the consequences.
Restorative theories of sleep suggest that sleep restores and repairs the body, making people feel refreshed in the morning. During sleep, the body produces growth hormones necessary for development in children and adolescents. These growth hormones also repair tissues and cells in people of all ages. The body also produces cytokines during sleep, which support the immune system in fighting infections.
Inadequate sleep can impact the body’s immune response to infection. Chronic sleep loss can make individuals more susceptible to common infections, such as a cold, while insufficient sleep over time can lead to a greater risk for immunodeficiency.
Getting appropriate sleep each night can help manage stress. When people wake up refreshed, they avoid the stressors that come with functioning while sleep-deprived, such as poor performance, difficulty thinking clearly, and lack of energy. Quality sleep can also reduce anxiety, depression, and other mental health strains related to stress.
Sleep is a key element of athletic recovery, and the body’s production of growth hormones is highest during sleep. These growth hormones are necessary for the repair of tissue and likely contribute to muscle growth. Most athletes require eight hours of sleep each night for restoration and to avoid overtraining and improve their performance.
Without sleep, athletes are at risk for lowered performance, fatigue, and changes in mood. Performing with less sleep also heightens the risk for injury. The potential for injury rises even more when an athlete’s sleep time decreases and time spent training increases.
Quality sleep, in addition to exercise, stress management, and healthy eating choices, is an important part of maintaining a healthy weight. During sleep, the body naturally produces more of an appetite suppressor, called leptin, while reducing production of the appetite stimulant ghrelin. On nights of too-little sleep, however, production of ghrelin increases and leptin decreases. As a result, a lack of sleep can lead to a greater feeling of hunger.
To get better sleep, and the many health benefits that come along with it, we take a look at the healthy practices around sleep, known as sleep hygiene. A number of lifestyle adjustments can help improve sleep quality.
A regular sleep and wake routine helps the body keep a consistent internal clock. Sleep experts recommend going to bed and getting up at the same time each day, including weekends.
Some adults like to nap during the day to avoid sleepiness. Keeping naps to about 20 minutes lessens fatigue without impacting sleep schedules. Naps that are too long can reduce alertness and defeat the purpose of napping. Individuals who choose to nap should avoid napping too late in the afternoon so that they can still fall asleep at their usual bedtime.
Although individual preferences may vary, most people sleep best in a dark, quiet, and cool bedroom. Too much light or noise at night can keep people awake or interrupt sleep. An eye mask or blackout curtains can eliminate unwanted light, and earplugs and noise machines can reduce distracting noises. Additionally, a fan can cool the room and serve as a noise machine.
Replacing old, worn, or uncomfortable mattresses and pillows with new and supportive ones can help improve sleep quality. The best mattresses and pillows for sleep depend on an individual’s preferred sleep positions and physical needs.
Caffeine is a stimulant that provides a boost of energy and alertness. When taken in the afternoon or evening, caffeine can make it difficult to fall asleep at night. The use of nicotine, found in cigarettes, in the evening is associated with more time spent awake at night. While some people drink alcohol before bedtime intending to get to sleep faster, alcohol is associated with lighter, lower quality sleep.
Daytime exercise can make it easier to fall asleep, and daily exercise is associated with better sleep quality. Exercise may also help individuals fall asleep faster and increase the overall time spent sleeping. It can be beneficial to exercise outside, as sunlight exposure during the day also improves sleep. People should avoid exercising too late in the day so that their bodies can relax before bedtime.
Setting electronic devices aside at least 30 minutes before bedtime can make it easier to fall asleep. Phones, tablets, computers, and other electronics with screens emit blue light, which can disrupt the body’s natural production of the sleep hormone melatonin and make it difficult to fall asleep.
Instead, sleep experts advise developing a relaxing routine in the hour before bedtime. During this period of winding down, choose a restful activity such as reading or taking a warm bath.
Those concerned about their sleep quality should consult with a health care provider. It may be helpful to keep a sleep diary to record sleep experiences and other symptoms. Discussing these symptoms with a doctor can identify potential causes for insufficient or interrupted sleep. Doctors can also talk through personalized strategies for improving sleep and refer individuals for additional testing as necessary.
The Sleep Foundation editorial team is dedicated to providing content that meets the highest standards for accuracy and objectivity. Our editors and medical experts rigorously evaluate every article and guide to ensure the information is factual, up-to-date, and free of bias.
The Sleep Foundation fact-checking guidelines are as follows: