Why Getting More Than 9 Hours of Sleep Every Night Could Be a Bad Thing
Sleep is important, you know that. Skimping on sleep means you’re courting all kinds of health problems down the line, from heart disease to obesity to diabetes. Still, that doesn’t stop many of us from doing it: More than a third of adults get fewer than seven hours of sleep a night, according to the CDC.
But what about the opposite side of the equation? Experts typically recommend that adults get seven to nine hours of sleep each night—so is it possible to sleep too much? Less is known on this topic, but it turns out that oversleeping also isn’t good.
Studies have linked oversleeping with myriad health problems, including a higher risk of death from any cause. In one large meta-analysis published last year in the Journal of the American Heart Association, the risk was shown to increase with each extra hour of sleep: Sleeping nine hours was associated with a 14% increased risk of dying, 10 hours with a 30% higher risk, and 11 hours with a 47% higher risk. The risk of dying from heart disease and stroke also increased with longer sleep times.
“In modern lifestyles, people have a tendency to intentionally restrict sleep because of working hours, caring duties for family members, hobbies, and other activities,” Chun Shing Kwok, MBBS, lead author of the study, tells Health. “Our evidence suggests that sleeping more than recommended may be more harmful than sleeping less.”
Other research suggests that habitually sleeping more than seven hours a night is associated with an escalating risk of diabetes. Yet another study found that “extreme sleep durations” (as well as not sleeping enough) was associated with higher levels of C-reactive protein, a marker of cardiovascular disease risk.
None of these studies proves that sleeping longer actually causes health problems or death. “We only demonstrate associations,” says Dr. Kwok, who is a clinical lecturer in cardiology and specialist registrar in cardiology at Keele University and Royal Stoke University Hospital in the U.K.
Any ideas as to why these associations exist are just guesses for now. “Sleeping longer duration may be an indicator for underlying ill-health, like a pre-existing condition that is not detected like heart failure, anemia, hypothyroidism, or obstructive sleep apnea,” says Dr. Kwok.
In other words, while sleep deprivation may actually lead to health problems, too much sleep is more likely to be an indicator that something is already wrong. “The association does not mean causality,” adds Robert W. Greene, MD, PhD, a professor in the departments of psychiatry and neuroscience at the University of Texas Southwestern Medical Center in Dallas. “The fact that you’re sleeping too much is probably not causing any problems per se but could be indicative that something else bad is going on.”
Keep in mind that individual sleep needs vary; you might be getting more than nine hours and be totally fine. If you’re used to sleeping 10 hours a night and have been catching that many zz’s for years, it’s probably nothing to worry about.
And don’t stress about one lazy Sunday morning. “Look for relatively acute changes,” Dr. Greene says. “If you used to be a seven-hour sleeper then all of a sudden you’re sleeping a lot more, that might be telling.”
If you think oversleeping could be a clue that something else is wrong with your health, the best thing you can do is head to a doctor. Figuring it out—and getting it treated—could help you start logging a healthier amount of shut-eye.
“Clinicians and patients should consider paying attention to how much they sleep as a symptom of ill health,” says Dr. Kwok. “Doctors should consider screening for problems related to sleep in consultations…as there are clear illnesses that are associated with tiredness that may result in increased sleep duration.”