Most of us would prefer a good night of sleep. We have more energy, we’re better able to focus, and we generally feel better the next day. But there’s growing evidence that sleep is really critical for maintaining good long-term health, too.

The body can usually cope with occasionally staying up late, but if you’re frequently or chronically depriving yourself of sleep, there will be health prices to pay, says Sigrid C. Veasey, MD, a researcher and professor of medicine at Penn Medicine in Philadelphia.

The strongest evidence may be in the fact that humans have not evolved to sleep any less than we did thousands of years ago, when people were sleeping outdoors and the dangers of being attacked by wild animals or the elements were much greater than they are now, Dr. Veasey says. If sleep really wasn’t that important, you could theorize that humans would have evolved to sleep less, she says.

“From an evolutionary perspective, that indicates sleep must be very important in some sense,” she says.

Getting too little or poor quality sleep can be the result of our personal choices: consuming too much alcohol or caffeine, spending lots of time before bed on our phones, or just not setting aside enough hours a night for sleep. Or it can result due to a another health issue (like undiagnosed sleep apnea, depression, or chronic pain) or a side effect of a medication we’re taking, explains Meena Khan, MD, a neurologist and sleep medicine specialist at The Ohio State University Wexner Medical Center in Columbus.

No matter the reason, however, poor sleep is bad for health, she adds.

According to guidelines from the American Academy of Sleep Medicine and the Sleep Research Society, published in June 2015 in Sleep, adults should sleep at least seven or more hours per night for optimal health.

Here are some of the long-term health problems you might be at increased risk of if you’re not clocking those hours:

1. Depression and Anxiety

Research shows that people who have chronic insomnia have a higher rate of depression and anxiety compared with people who haven’t been diagnosed with insomnia, says Dr. Khan. Estimates suggest 15 to 20 percent of people diagnosed with insomnia will develop major depression.

The relationship between mood and sleep is complex and bidirectional, which means that depression or anxiety can worsen sleep, and lack of sleep is can also negatively impact mood. And insomnia is considered an independent risk factor for developing depression in people of all ages, according to a review February 2019 in the Journal of Cellular and Molecular Medicine.

Sometimes separate treatments are needed to help with the sleep problems and the anxiety or depression, but in some cases improving sleep can help mood, too, says Khan. A meta-analysis of 23 studies, published in August 2018 in Depression and Anxiety, that looked at the effects of insomnia treatment on depression found that treating the insomnia had a positive effect on mood.

2. Type 2 Diabetes

Poor quality sleep or short sleep duration has been linked to poorer blood sugar control in people with and without diabetes, says Khan. It can increase risk of the development of diabetes as well, she says.

One recent study, published in September 2020 in Diabetologia, found that insomnia may increase risk for type 2 diabetes by as much as 17 percent.

3. Weight Gain and Obesity

Laboratory research suggests that not getting enough sleep can lead to metabolic changes associated with obesity; and observational studies that look at duration of sleep and rates of obesity have found a link between the chronic metabolic disorder and not getting enough regular rest, according to the Centers for Disease Control and Prevention (CDC).

The link is particularly strong in children.

In the Nurses’ Health Study, which followed 68,183 women over 16 years, those who slept an average of five hours or fewer per night had a 15 percent higher risk of developing obesity compared with women who slept five hours per night.

The women who slept less were also 30 percent more likely to have gained 30 pounds over the course of the study compared with women who slept longer.

4. Hypertension, Heart Disease, and Stroke

The American Heart Association (AHA) includes sleep in its checklist of modifiable factors that can improve heart health; the list is called “Life’s Essential 8” and is published in the journal Circulation. The list also includes diet, exercise, tobacco use, weight, cholesterol, blood sugar levels, and blood pressure.

Studies in large groups of people that have compared poor sleep and sleep problems with heart attacks and stroke have shown that worse sleep is linked to those heart problems, according to the Heart Foundation.

A study published in June 2020 in PLoS Biology identified a possible mechanism whereby worse sleep could be harmful to the heart; it showed that sleep fragmentation (repeated awakenings through the night that disrupt sleep) was associated with of the buildup of inflammation in the arteries (specifically white blood cells called monocytes and neutrophils), which leads to atherosclerosis (the buildup of plaque on and inside the artery walls).

There is also evidence linking sleep disorders (which tend to result in poorer quality or shorter sleep) with heart problems. People with obstructive sleep apnea (OSA) have higher risk of hypertension, heart attack, and stroke, says Khan.

5. Kidney Problems

The link between sleep and kidney health hasn’t been as firmly established as the link between sleep and other chronic conditions, says Khan. “There have been a few preliminary studies, but the relationship needs to be further explored,” she says.

Chronic insomnia was associated with the development and progression of chronic kidney disease, but not end-stage renal disease or death from any cause, according to research published in 2018 in Mayo Clinic Proceedings.

6. Cognitive Problems, Alzheimer’s Disease, and Other Types of Dementia

“What we're finding is that injury due to poor sleep or not enough sleep doesn't show up immediately, but it can result in changes that later on in life look like Alzheimer's disease and injury in the hippocampus and some of the other brain regions,” says Veasey. The hippocampus is one of critical areas for learning and memory, she adds.

A study published inJanuary 2019 in the journal Translational Medicine, for example, found that older people who had comparatively less deep sleep than others had greater amounts of tau protein, which is associated with Alzheimer’s disease progression.

The same effect has been found in younger individuals too, in subsequent research published in March 2020 in Neurology.

And there’s evidence linking sleep deprivation with increased production of beta-amyloid (a protein linked to Alzheimer’s disease); research published April 2018 in Proceedings of the National Academy of Sciences indicated this effect can start after just one night of sleep deprivation.

Research from Veasey’s team in animal models, published in November 2018 in the Journal of Neuroscience, suggested the damage that accumulates is lasting — and likely can’t be remedied from subsequently sleeping “extra” or sufficiently even for long periods of time.

7. Impaired Immune Function

Not getting enough or good enough quality sleep can shortchange your immune system, says Khan. “There is evidence that getting plenty of sleep can benefit your immune system and that impaired sleep is linked with being more susceptible to infections.”

One study published in January 2017 in Sleep, for example, examined the blood samples from 11 pairs of twins and found that the twin who slept less had a depressed immune system compared with the sibling who got adequate sleep.

A previous study found that people who slept for less than six hours a night were far less likely to mount antibody responses to a standard three-dose hepatitis B vaccine and were significantly more likely to be unprotected by the vaccine compared with people who slept an average of more than seven hours of sleep per night.

And there is evidence that important functions of the immune system (growth and production of various immune cells) only happens during sleep.

8. A Less Healthy Gut

The gut microbiome is all the microorganisms such as bacteria and fungi that are found in the gastrointestinal tract. Research published in June 2018 in The BMJ suggested that the more diverse the microbiome, the better it is for overall health. Lower bacteria has been observed in conditions such as inflammatory bowel disease (IBS), type 1 and type 2 diabetes, obesity, and psoriatic arthritis.

There are some studies that suggest that altered sleep — for example, what night shift workers would experience — may impact your gut health, Khan says. “But that research is still in the beginning stages.”

Research published in October 2019 in PLoS One that looked at the microbiomes of 26 men found that total microbiome diversity was positively correlated with increased sleep efficiency and total sleep time was negatively correlated with waking after sleep had started.

The study’s authors concluded in the paper: ”The diversity of the gut microbiome promotes better sleep.”

Editorial Sources and Fact-Checking

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8 Health Problems Linked to Not Getting Enough Sleep