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Olivia: When people talk about having “too much of a good thing,” they usually mean overindulging in something like cake or fast food — things you probably enjoy, even if they aren’t that good for you. But what about something that’s objectively important to your health and well-being, like sleep?

Well, it turns out that you can get too much of that, too. Most people need 7-9 hours of sleep, and oversleeping is connected to health problems like depression, heart disease, and diabetes. A 2014 study of 894 pairs of twins, for example, showed that the genetic risk of depression was higher in subjects who got less than 7 hours of sleep or 9 or more hours of sleep every night.

Meaning, people who overslept or under-slept or were more likely to be depressed because of genetic factors, as opposed to environmental ones. And according to a study on the sleep habits of 400,000 Taiwanese adults, the risk of coronary heart disease is about the same in people who sleep less than 4 hours a night as it is in those who sleep more than eight hours a night. Subjects who under-slept had a 35% higher risk of heart disease, and people who overslept had a 34% increase.

Another study, published in 2009, followed 276 subjects for six years and found that people who slept either less than 7 hours or more than 8 hours were at least twice as likely to develop type 2 diabetes or trouble tolerating glucose. There’s more: A 2013 study of about 54,000 adults over the age of 44 found links between too much sleep and increased rates of heart disease, diabetes, obesity, stroke, and mental health issues. In fact, the rates of coronary heart disease, diabetes, and stroke were even higher in people who overslept than in those who slept too little.

So, the links are there. Sleep correlates with all kinds of health problems. But it’s hard to say whether too much sleep actually causes these issues. It’s totally possible that oversleeping is actually a symptom of things like depression or heart disease, or that there’s some other connection. Either way, consistently sleeping too much might be a bad sign.

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