When it comes to sleep, it *is* possible to have too much of a good thing

Slacking in the sleep department can lead to serious problems: Clocking minimal shut-eye each night can affect your memory, stress level, and even stifle your #girlboss potential by making you feel like you’re drunk at work. Yeah, not cool. But unfortunately, the solution isn’t as simple as catching more zzz’s: A new landmark study linked sleeping more or less than 7 to 8 hours with a higher risk of cardiovascular disease and even death.

The study, published in the Journal of the American Heart Association, analyzed data from more than 3 million subjects of past studies and found that snoozing past the prescribed mark is particularly harmful for a person’s longevity. Sleeping for 9 hours per night resulted in a 14 percent higher risk of death among participants, while 10 hours of shut-eye spiked that risk up to 30 percent, according to Medical News Today. And quality—not just quantity—of slumber mattered, too: The results showed that those who reported sleeping poorly risked having a 44 percent higher risk of coronary heart disease.

Snoozing past the prescribed mark of 7 to 8 hours was linked to increased risk of death.

And these findings are hardly the first to note the benefits of getting *just* the right amount of sleep. Another study published in the journal BMC Public Health notes that sleeping too much or too little can actually increase a person’s likelihood of sustaining metabolic syndrome, which is a cluster of symptoms including high blood pressure and abnormal cholesterol that increase risk of heart disease, stroke, and diabetes, Mayo Clinic reports. Researchers asked more than 133,000 Korean men and women aged 40 to 69 to fill out a questionnaire inquiring about their sleep routines. The answers were then compared to participants’ personal data collected in a previous study. Sleep duration from the questionnaire was divided into four categories: less than 6 hours, 6 to 8 hours, 8 to 10 hours, and more than 10 hours.

The results showed there’s a definite sweet spot when it comes to how many hours you should spend between the sheets (sleeping, that is). Compared to people who slept six to eight hours a day, the men who slept less than six hours were more likely to have metabolic syndrome and a higher waist circumference, and the women were more likely to have higher waist circumference.

However, sleeping more than 10 hours per day was found to bring about its own host of health issues. (So it seems there’s a limit on being able to pay off your sleep debt on weekends.) For men, the super-sized sleep time was associated with metabolic syndrome and increased levels of triglycerides. The same was true for women—with the addition of a higher waist circumference, increased levels of blood sugar, and low levels of “good” cholesterol.

Researchers think the connection between long sleeps and metabolic syndrome has something to do with hormones. When elevated, they can make you hungrier (thereby leading you to eat more) and cause your energy levels to plummet—two things that can certainly play a role in weight-gain and obesity.

But, despite being the largest study on the correlation between sleep and metabolic syndrome, according to Newsweek, a major caveat of the BMC Public Health study is that the participants self-reported their sleep routine, leaving room for error. Participants may have, for example, noted time spent snuggling in a cozy bed as “sleep.”

Even so, it’s not a bad idea to work on finding your own REM sweet spot. As tempting as it is to sleep in on the regular, it might not be doing your health any good—just like staying up all night or having ever-changing bedtimes. Once you determine your happy medium, you’ll be a happy snoozer and feel healthier overall.

Originally published June 13, 2018; updated on August 9, 2018, with additional reporting from Kells McPhillips. 

Try Bella Hadid’s tip for getting a restful night of sleep. Or, try three ways to optimize your circadian rhythm for better sleep.