You’ve likely noticed that when you get a good night’s sleep, you feel better the next day. But the benefits are broader than that: Sleeping well can profoundly influence your health and well-being.
Here’s an overview of some of the effects sleep can have on your health, as well as some of the ways a lack of quality sleep can affect your health.
Appearance
For starters, when you’ve gotten enough sleep, it’s reflected in your appearance. (Hence, the term “beauty sleep.”) Facial skin is better hydrated and looks brighter overall, and dark under-eye circles may appear less prominent. On the flip side, insufficient sleep can make you look tired: The eyes may appear red or swollen, and the eyelids and the sides of the mouth may appear to droop.
Being well-rested also can enhance how friendly and approachable you seem to others, whereas visible signs of fatigue can be a “social repellant.” As one study found, participants were less likely to want to interact with sleep-deprived subjects and even perceived them as seeming lonelier.
Mental health and flourishing
When well-rested, you’re better equipped to handle stress and more emotionally resilient.
In one study, participants’ perceived sleep quality affected their mood the next day: Higher sleep quality was linked to a more positive mood. Additionally, quality sleep helps with emotional regulation. (The opposite is also true: Sleep loss also intensifies feelings of anger, several studies have shown.)
There are also longer-term implications for flourishing, a broader measure of psychological well-being. As one new study found, participants’ overall sleep — including not just the number of hours they logged but their perceived sleep quality — affected how highly they rated various aspects related to flourishing, including their sense of purpose and meaning, their optimism levels, and their perceptions of their overall competence.
When it comes to mood disorders, sleep is also a key consideration. As noted in a new study in the Journal of Adolescent Health, not getting enough sleep increased the likelihood of major depression within the next five years. That said, it’s also important to note that the effects are bidirectional: Just as poor sleep can affect mood and exacerbate mental health issues, mental health issues themselves can contribute to sleep issues.
Brain health and functioning
Getting enough quality sleep also has broad effects on cognition, everything from the ability to think clearly to longer-term memory and brain health.
Sleeping well makes it easier to retrieve information, whether remembering what’s on your daily “to-do” list or recalling something you read the day before. It also means it takes less effort to focus on the task at hand, although this type of intentional concentration can also help offset some of the ways working memory is more sluggish after a night of poor sleep.
Given the essential role of sleep in processing and remembering information, logging enough hours also affects your cognitive performance. One study found that adults who slept 6 to 8 hours performed better on a series of cognitive tasks assessing working memory and processing speed than those who slept just 3 to 6 hours.
It’s not just next-day functioning that’s affected, however: There are also longer-term implications to consider.
In one new study published in Neurology earlier this year, researchers found that participants with poor sleep quality (specifically, sleep fragmentation) in their mid-30s to late 40s were more than twice as likely to post low scores on cognitive tests 11 years later.
Another new study published in the Journal of the American Heart Association found that brain health markers (assessed by MRI) differed based on sleep duration. Compared to adults who slept 7 to 9 hours, those who logged fewer than 7 hours of sleep were more likely to have several neuroimaging markers, including brain white-matter lesions (known as white matter hyperintensities), which are early indicators of future strokes or dementia.
That may be due in part to the impact of poor sleep on the glymphatic system, which has been called the brain’s garbage disposal system. “When we sleep, the glymphatic system gets rid of toxic waste products, including those that can otherwise build up and lead to Alzheimer’s and other neurodegenerative conditions,” explains Dr. Beth Malow, professor of neurology and pediatrics at Vanderbilt University and director of the sleep division.
Fitness and sports
It’s well-known that regular exercise helps you sleep better at night, but there are also numerous ways that sleeping well affects your sports performance, whether you’re an elite athlete or simply trying to keep to a regular fitness routine.
That’s because sleep boosts key athletic markers, including coordination, response time, and endurance. In fact, one recent review, which synthesized the results of 25 studies focusing on a variety of sports, found that getting more sleep improved athletes’ reaction time and improved their performance.
In light of this, it’s not surprising that logging enough hours helps reduce the risk of injury. And if you get injured, sleep is key for healing and recovery, given the essential role of growth hormone (primarily released during deep sleep) in the healing process.
To sum up, sleep affects “the things that athletes care about the most, including mental performance, physical performance, and injury risk,” says Michael Grandner, Ph.D., director of the Sleep and Health Research Program at the University of Arizona.
Weight management
Making healthy food choices and maintaining a healthy weight are both easier when sleeping well is part of the mix.
Logging enough hours helps keep the two hormones that regulate feelings of hunger, leptin and ghrelin, in balance. Without enough sleep, we feel hungrier and may crave foods that are higher in sugar. In addition, spending more time awake increases the potential window for eating, which can also lead to increased caloric intake.
These sleep-influenced behaviors contribute to the likely link between sleep and obesity risk, which in turn has numerous implications for overall health. And it’s not just how many hours you sleep that matters: In a study that analyzed sleep data from more than 120,000 adults, those whose body mass index was 30 or above (considered the threshold for obesity) got about 15 minutes less sleep but also had more variable sleep schedules.
In fact, improving sleep can be a way to help people meet weight-loss goals. One study published in JAMA Internal Medicine included two groups of overweight adults who regularly averaged less than 6 and a half hours of nightly sleep. All participants kept their diet and exercise routines the same, but those in one group received personalized sleep hygiene advice while the others did not. The result? After two weeks, participants in the first group increased their nightly sleep by more than an hour and consumed about 270 fewer daily calories than those in the second group. They also lost about a pound over the two-week timeframe, while their counterparts gained close to a pound.
Moreover, getting enough sleep makes it easier to maintain weight loss. One recent study found that when adults who’d lost weight were evaluated one year later, those who averaged at least 6 hours of sleep a night regained less weight and had a greater decrease in body fat percentage compared to those who clocked fewer hours.
Cardiovascular and metabolic health
There are numerous ways that sleeping well can be a protective factor against longer-term health risks such as cardiovascular disease, an umbrella term that includes coronary heart disease and stroke. That’s because of the link between poor sleep and several other risk factors, including atherosclerosis (plaque buildup in the arteries) and metabolic disorders such as diabetes.
While the American Heart Association now includes sleep duration on its list of eight essential behaviors for cardiovascular health, sleep consistency is just as important, if not more so.
A recent study in the Journal of the American Heart Association found that participants whose sleep varied by at least 2 hours from one night to the next were more likely to have calcified plaque in their arteries, which is linked to cardiovascular disease.
Sleep duration and variability are also important considerations for diabetes, a metabolic disease in which glucose levels are too high. “We don’t metabolize blood sugar properly when we’re sleep-deprived,” Malow says. “There’s also increased inflammation when we’re not sleeping well, which can lead to heart disease or stroke.”
A study published earlier this year in JAMA Network Open reinforced that the amount of sleep you get affects your likelihood of developing diabetes, which in turn doubles your risk for both heart disease and stroke. After analyzing the health data of close to 248,000 adults, the researchers concluded that those who slept 6 or fewer hours were more likely to develop type 2 diabetes (adult-onset diabetes), regardless of their diet.
Meanwhile, another recent study of adults with type 2 diabetes found that those whose sleep was more variable were more likely to have higher systemic inflammation, which increases the risk of cardiovascular disease.
Longevity
The evidence continues to mount that sleeping well can boost your life expectancy.
That’s not just based on what’s noted above about the links between poor sleep and heart disease, which remains the leading cause of death in the United States.
One new study analyzed health data from more than 172,000 adults, specifically looking at five aspects of sleep quality, including duration, insomnia, and feeling rested upon waking. The researchers found that the adults with the healthiest sleep patterns were the least likely to die early, even after controlling for other factors.
That’s in keeping with other recent research highlighting the link between sleep and longevity. One recent study of about 61,000 adults found that both irregular sleep and short sleep were associated with a higher risk of dying from cardiovascular diseases. Overall, however, when it came to lowering mortality risk, consistent sleep was found to be even more important than sleep duration.
What to focus on to improve your sleep
It’s clear that sleeping well can have serious benefits, but how do you know where to start? Sleep duration is often the first aspect that comes to mind, but timing and consistency are increasingly recognized as being just as important, if not more so.
By any measure, however, the reality is that for many of us, committing to making any improvement will help. A recent study of more than 67,000 adults found that only about 15% regularly attain the recommended 7 to 9 hours of nightly sleep, and even when they do, their sleep is often inconsistent.
“Work toward sleep consistency, and work toward getting at least 7 and a half hours a night,” suggests Malow, who notes that it can be an ongoing process: “If you have a rough night once in a while, it’s not the end of the world.”
