Sleep and Physical Health
It’s no exaggeration to say that sleep is among the most powerful tools humans have at their disposal to improve their physical health. During sleep, the body undergoes critical repair processes that help fight illness, heal wounds, and recover from the stresses of day-to-day life. Adequate amounts of restful sleep have been convincingly tied to a healthier body (both inside and out), a better immune response, and a longer life.
But sleep deprivation, unfortunately, is all too common—particularly in the U.S.—and may be at least partially to blame for many maladies that are common today. Prioritizing sleep isn’t always easy, but it may help people, on both the individual and societal levels, boost their health and potentially reduce their healthcare costs.
Most people are well-aware of how much better they feel, both mentally and physically, after a night of great sleep. But good sleep does much more than providing the brain and body with a boost of energy. It actually repairs them on a cellular level, addressing damage accumulated over the course of daily life and strengthening key systems that help the body fight disease, improve fitness, and look and feel healthier. Sleep has a beneficial effect on almost all of the body’s major systems—from the cardiovascular system to the muscular system to the digestive system—and could be key to fighting many of the “diseases of civilization” that wreak havoc in the modern world.
Yes, evidence suggests that adequate amounts of restful sleep are good for the heart. Both sleeping too little and sleeping too much have been linked in large studies to an increased risk of cardiovascular disease, heart attacks, and increased blood pressure. Consistent nightly sleep, on the other hand, has been associated with a decreased risk of heart problems; napping during the day may also provide some benefit. Though the exact reason isn’t fully understood, researchers speculate that time spent asleep is less stressful for the heart than time spent awake, and may lower levels of cortisol that can contribute to heart problems.
There’s a reason that those who are sick are advised to get plenty of rest: A substantial body of evidence finds that sleep helps the body fight infections and boosts general immunity. During sleep, the immune system releases cytokines, proteins that help the body fight and ward off infection. When sleep is disrupted or inadequate, the immune response is depressed, making the body more susceptible to getting sick or to a more prolonged recovery.
During sleep, the body produces crucial hormones that help repair different parts of the body, including the skin and muscles. When someone is sleep-deprived, the body produces less collagen as a result of the decrease in hormones, causing skin to lose elasticity and firmness (leading someone to “look tired” the next day). Over time, this cycle can damage the appearance of the skin, triggering wrinkles, sagging, or reductions in thickness. On the other hand, adequate amounts of sleep can promote firm skin, help maintain muscle mass, and protect bone health, all of which can have beneficial effects on one’s appearance.
In a sense, yes. Research suggests that individuals are judged to be more attractive and healthier when they are well-rested, compared to when they aren’t. Sleep also supports an improved mood and better overall health, both of which can contribute to a more attractive external appearance.
While no amount of sleep can help someone live forever, there is consistent evidence that sleep is essential to overall health and, perhaps, a longer life. Sleep deprivation has been linked to lower resistance to disease, cardiovascular problems, dementia, and an increased risk of accidental death. Averaging between 7 and 9 hours of sleep each night, on the other hand, has been associated with a lower risk of all-cause mortality in several large studies.
Sleep helps the body preserve muscle mass, which can have beneficial effects on one’s ability to maintain an exercise routine and become stronger over time. Longer sleep times have also been tied to increased fat loss, which may have positive downstream effects on an exercise regimen.
Conversely, regular physical activity is essential for healthier, more restful sleep. Research has found that exercise is linked to increased time spent in deep sleep, a phase of sleep critical for restoring immune function and supporting physical health. Exercise can also significantly reduce stress and anxiety, which may make it easier for someone to quiet their mind and fall asleep at night. Exercise is also a well-supported intervention for several sleep disorders, including insomnia and sleep apnea.
It’s very possible. In studies of both men and women, longer sleep duration has been associated with heightened sexual desire; in one study, each hour of additional sleep increased the likelihood of having sex the next day by 14 percent. These effects appear to occur over both the short- and long-term, in that consistent sleep is also associated with more consistent sexual arousal over time. Conversely, sex can increase sleepiness and improve sleep quality.
Anyone who has suffered through a night of insomnia knows that the next day, they feel fatigued and sluggish; they may even feel as if they look significantly worse. But the effects of poor sleep are more than just mental; sleep deprivation, especially when it happens over the long term, is strongly associated with worse heart health, a weakened immune system, and a heightened risk of obesity, diabetes, sexual dysfunction, and even certain kinds of cancer. Understanding the myriad ways that poor sleep can hinder health may help motivate someone to make sure they’re consistently getting a good night’s rest.
Many people are well-aware that sleep deprivation is bad for the heart. But some evidence also suggests that excessive sleep—that is, regularly sleeping significantly more than the seven to eight hours recommended by most experts—may come with a similar risk of cardiovascular disease or heart attacks. In our sleep-deprived society, many people see little risk in sleeping too much. But individuals who feel like they are consistently sleeping for extended hours at night, or who continue to feel groggy even after several nights of consistent sleep, should discuss the situation with their doctor; oversleeping may not be as benign as commonly thought.
Poor, disrupted sleep has been associated with a significantly increased risk for Type 2 diabetes. Though more research needs to be done to fully understand the connection, researchers speculate that sleep’s influence on metabolism, hormone production (including hormones that regulate appetite and satiety), and the body’s use of blood sugar may play a role. Similarly, insufficient sleep increases the risk of obesity, itself consistently associated with an increased occurrence of diabetes.
Some studies suggest that poor sleep is linked to a greater risk for certain types of cancers, including breast, prostate, and thyroid. After diagnosis, sleep problems may also be associated with more severe and aggressive disease progressions. Those in shift work—who either work a long-term night shift or who have inconsistent work schedules that disrupt their sleep—appear to be at significantly increased risk of many types of cancers, research shows.
It’s possible. Overall, poor sleep is tied to a heightened risk of obesity. Research suggests that the link between sleep habits and weight gain may have several potential explanations: decreased energy after a poor night of sleep reduces the likelihood that someone will exercise; disrupted sleep interferes with the production of hormones that regulate appetite, metabolism, and insulin production; sleep deprivation is associated with increased craving for fatty, high-sugar foods; and more time spent awake often results in more food being consumed. Practicing healthy sleep habits—combined with exercise and dietary changes—may help someone who wishes to lose weight.
Evidence from brain scans suggests that when someone is sleep-deprived, the reward centers of their brain are more likely to respond strongly to unhealthy, high-calorie foods than when they’re well-rested. A night of poor sleep has also been associated with worsened impulse control the next day, potentially making it more likely that someone would give in to a craving for junk food. And when it comes to food choices, quantity matters, too; sleep deprivation decreases the production of leptin, a hormone that helps suppress appetite and signal fullness to the brain, making it more likely that someone will eat greater amounts of food than they normally might.
It can. The decreased hormone production that is a hallmark of sleep also affects sexual hormones like estrogen and testosterone; lower levels of testosterone, in particular, are tied to sexual dysfunction, especially in men. Poor sleep may also worsen an individual’s sex life simply because sex takes energy; if someone is overtired, they may be significantly less likely to put in the effort to have sex with a partner.