Eight Hours of Sleep Isn’t Right for Everyone, So Why Do We Keep Pushing That Number?

Like diets, maybe we should be taking an individualized approach to rest.

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The phrase, “I’ll sleep when I’m dead” has me sprinting toward the grave. I am a Sleeper. I love my sleep, I never sacrifice it and I can never truly get enough of it. Yet despite my allegiance to slumber — or perhaps because of it — I’m constantly tired.

Culturally, eight hours of sleep is considered the perfect amount. It’s partially why we have an eight-hour workday — eight hours for work, eight hours for rest, eight hours for what you will. But if you’ve ever, you know, lived in society, you’ll have noticed that there’s plenty of variances to that number. I prefer closer to nine hours of sleep, while, terrifyingly, there are people who walk this Earth feeling comfortable at five. So what gives?

Eight hours has long been considered the norm for a few reasons. For many people, it is indeed the ideal baseline. In a 2010 study, researchers analyzed 25 years of data covering 1.3 million people and found that those who slept less than seven hours a night were 12 percent more likely to experience premature death, while those who slept more than eight hours were nearly 30 percent more likely to experience premature death. Just under eight hours is, therefore, the biological sweet spot for most people.

But more recent data provides a little wiggle room. People between the ages of 18 and 64 need between seven to nine hours of sleep on average, according to the National Sleep Foundation. These figures are based upon the recommendations of a panel of experts consisting of 18 people from various health organizations, including the American Neurological Association and the American Academy of Pediatrics. The panel conducted a literature review of sleep studies published from 2004 to 2014, and collectively formed their recommendations accordingly. The panel further identified that among adults under 65 years of age, as little as six and as many as ten hours of sleep “may be appropriate for some.” Any more or less sleep isn’t recommended, but still, you’re essentially left with four hours of possibility here.

By some accounts, though, all these numbers are entirely arbitrary. In a study published earlier this month in the academic journal Sleep, 613 participants were studied over a period of 28 years. During this time, participants reported how many hours of sleep they got, had their cognitive abilities tested and their gray and white brain matter measured. They ultimately concluded that there were no differences in cognitive abilities or brain structure correlating to sleep quantity at all.

Regardless, most of us can tell the difference between being well-rested and not. Maybe my gray matter is just fine, but I feel freaking exhausted on less than eight hours of sleep. I might technically be able to complete my tasks with the same cognitive capacity, but I won’t like it!

Meanwhile, there are plenty of sick people out there thriving on five hours. In September, scientists pinpointed a gene shared among people who reportedly feel just fine on less than six hours. It’s rare — only about one in four million people carry it. Those that do, though, don’t experience the adverse health effects of insufficient sleep — their bodies truly do only require a few hours of rest to properly function. Other studies suggest that nearly 30 percent of people are “habitual short sleepers” who get by just fine on less than the recommended dose of snoozing.

For the rest of us, though, a lack of sleep has been linked to just about every type of ailment, from dandruff to intestinal cancer. On a more immediate level, not getting enough rest means we’ll feel tired, plain and simple.

Perhaps, then, we should be looking at sleep the same way we do our diets — that is, everyone should take an individualized approach, rather than all of us striving for a number that, for many of us, doesn’t actually work (much like most of those non-personalized diets). Of course, there are certain parameters to follow: Adults should eat somewhere between 1,600 to 3,000 calories a day depending on body size and activeness, though some outliers will be comfortable on less or require far more. Most of us will also need somewhere between seven to nine hours of sleep, and some will do best at a different number of hours.

Your ideal quantity of sleep is, therefore, whatever amount allows you to get through the day feeling happy, productive and alert. It’s basically just, like, your opinion, man.