Is there such a thing as too much sleep?

For some people, sleeping in as long as possible, totally unfettered by an alarm clock, is the ultimate weekend fantasy. But unfortunately, oversleeping isn’t healthy, according to medical experts. In fact, it's been tied to serious health conditions. We got the low-down on what counts as too much sleep, plus what excessive sleep can mean for your body.

How much sleep do you need?

It all depends on your age and genetics, but seven to nine hours of sleep per night is optimal for most adults, says Dr. Kathryn Boling, a primary care doctor at Mercy Medical Center in Baltimore, Maryland.

Some groups of people, such as babies and teenagers, need more sleep. There are also people who might require more shut-eye based on genetics. Boling says there’s no way to know for sure if someone is predisposed to sleeping longer. But if you’ve been sleeping extra hours your entire life that could be an indication that you’re a naturally long sleeper.

How much sleep is too much?

Sleep experts and medical professionals say that there is such a thing as too much sleep. Per Boling, “Sleeping too little or too late actually both have bad consequences."

Sleeping more than nine hours is of particular concern for arthritis sufferers because inflammation can worsen with extended non-use of joints, Boling says. Regularly spending too long in bed can also worsen back pain, particularly if a person sleeps in a position without adequate support. Boling says that if you’re having back pain, you might want to check for signs that you need to replace your mattress and make sure your bed pillows are supportive. (P.S. Sleeping without a pillow isn't great, either.)

Occasionally oversleeping may seem relatively harmless. But it can negatively impact your sleep schedule, even after only one day, according to Michael Breus, a clinical psychologist who specializes in sleep.

For example, some people will sleep a few extra hours one night if they’ve had a stressful week, or perhaps they stayed up too late the night before. Unfortunately, this practice doesn’t make up for not getting regular sleep. In fact, Breus says that sleeping past your usual wakeup call can further throw off your circadian rhythm by delaying the production of melatonin, the sleep hormone that helps control your sleep and wake rhythm.

Serious health problems are associated with too much sleep

Breus says it’s important to make a distinction between hypersomnia and oversleeping. Most people are tempted to oversleep on occasion. Hypersomnia is a medical diagnose where people feel tired during the day, wake up feeling tired, and regularly want to sleep more than nine hours a day, among other conditions. Research has linked hypersomnia to heart disease, dementia, and depression, and other chronic illnesses.

“​​Most people who come to see me who are reporting that they are sleeping a long time usually do have something going on,” Boling says, adding that daytime fatigue can also be tied to thyroid problems and anemia.

Sleep apnea, another disorder linked to hypersomnia, might prevent people from feeling well rested because sufferers are getting poor quality sleep without realizing it, Boling says. But it isn’t always clear whether excessive sleep worsens these conditions or is caused by them. Depression can make people feel like they don’t want to get out of bed, but it is also possible that staying in bed worsens depression, Boling says.

Another example of this: A 2021 study from Spain surveyed the sleep patterns of 2,536 pregnant women and found that lower birth weights were associated with sleeping more than nine hours at night. But the study couldn’t say that sleeping more causes low birth weights.

Author Jordi Julvez Calvo, a psychologist and epidemiologist, says more research is needed to determine why this might be. Although the study attempted to control for health problems, he says the mothers who slept more could’ve had an underlying condition that also impacted birth weight.

It’s also important to remember that sleep deprivation is a problem, too. In that same study, lower birth weights were also associated with pregnant women who slept fewer than seven hours.

Boling adds: “The majority of adults that I see don't have the problem of oversleeping, they have the problem of undersleeping.”

How do you know if your sleeping pattern is a problem?

There’s no easy way to tell whether you have an underlying condition that’s leading to excessive sleeping. The experts we spoke with say it’s important that people who might be suffering from hypersomnia see a doctor. Boling says issues like sleep apnea, anemia, and depression can be treated with medical help.

"If you feel like you're tired all the time, you definitely want to talk to your doctor about seeing a sleep specialist,” Breus says.

He adds that a sleep study may be needed to determine whether a patient has hypersomnia or other medical conditions before accessing treatment. Sometimes it turns out that the person simply has a bad sleep environment—ahem, noisy neighbors—that prevents them from getting quality rest.

How can you improve your bedroom environment?

Part of getting a good night’s rest has to do with sticking to a nighttime routine. But if you’re getting poor sleep because of environmental factors, we’ve got other sleep hygiene tips for your bedroom, too.

• Drown out noisy neighbors with a sound machine. Loud, jarring noises can disrupt your sleep. But there are some good kinds of noises. Turns out, rain noises can actually help you fall asleep. We recommend the Sound + Sleep by Adaptive Sound, which features rain and ocean sounds in addition to white noise. Our tester said it “produced clear highs and soothing bass, without distortions.” You might also consider wearing earplugs at night if you’re dealing with a snoring partner.

• Banish stray light with a sleep mask. Nocturnal light can throw off your circadian rhythm. We’re fans of the Nidra Deep Rest eye mask because it stays on all night without putting pressure on your eyes. For those who want to feel extra fancy, we’ve also reviewed the Lunya sleep mask. Rather not wear something? Blackout curtains may be the answer.

• Replace your mattress. If you haven’t purchased a new bed in more than 10 years, it may be time to look into getting a new one. We’ve reviewed plenty of the best mattresses in a box, including the Leesa and Purple.