Mind & Body

Too Much Sleep May Be Just as Harmful as Too Little

Work was brutal this week, and as a result you got less than five hours of sleep every night. Finally, the weekend is here and you're ready to earn those lost hours back with luxurious, back-to-back nights of 10-hour sleeping marathons. Well, science is here to tell you to reconsider that plan. Not only will you probably feel more tired, that extra sleep could also take a toll on your health.

There's Such a Thing as Too Much Sleep

We all know there are risks associated with getting too little sleep. Chronic lack of sleep is linked to a higher risk of obesity, heart disease, depression, and even early death. Well, it turns out, chronic oversleeping carries the same risks.

In 2016, a study in the International Journal of Cardiology delved into the sleep habits of nearly 400,000 Taiwanese adults over seven years. It found that when compared to people who slept six to eight hours per night, those who slept less than four hours per night increased their risk of dying from heart disease by 34 percent. Those who slept more than eight hours per night? Nearly identical — their risk increased by 35 percent. Likewise, a 2015 study in the journal Neurology found that people who slept more than eight hours a night experienced a higher risk of stroke, and a 2009 study in Sleep Medicine found the same thing for type II diabetes risk.

But hold on, you might say. These are just correlations. What if it's a person's lousy health that leads to oversleeping, and not the other way around? Excellent point. Luckily, in 2014, a team of researchers studied the genetics behind these sleep-based health effects with nearly 900 pairs of twins for a study published in the journal Sleep. By using statistical models that examined genetic interactions, they were able to figure out how much a health issue like depression was influenced by genetics — that is, how much it was inherited and how much it was due to a person's environment — and whether sleep had an effect on that heritability. They found that while depressive symptoms had a heritability of about 27 percent in people who got around seven to nine hours of sleep per night, for those who got less than seven or more than nine, the heritability hovered around 50 percent. That's right: under- and oversleeping actually messes with your DNA.

How Much Sleep Is the Right Amount?

How much sleep is too much (or too little) depends on a number of factors, particularly your age. The National Sleep Foundation recommends that adults get somewhere in the ballpark of seven to nine hours of sleep per night, though some can get away with as little as six or as much as 10. Generally, if you're waking up feeling well rested without nagging headaches, back pain, or grogginess, you're probably fine. If you think you might not be sleeping the right amount, however, it's important to try your best to get to bed on time—and get out of bed on time, too.

Need to improve your sleep habits? Check out "Sleep Smarter: 21 Essential Strategies to Sleep Your Way to A Better Body, Better Health, and Bigger Success" by Shawn Stevenson. We handpick reading recommendations we think you may like. If you choose to make a purchase through that link, Curiosity will get a share of the sale.

Can You Sleep Too Much?

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Written by Ashley Hamer January 10, 2017

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