7. Death
In a 2010 study published in Sleep, researchers from the University of Warwick in the U.K. found an association between early death and both too little and too much habitual sleep.
“Short sleep duration has been linked to earlier mortality,” Kushida says. The link is stronger for people, especially men, who have sleep apnea, but it’s also been linked to men who sleep less in general.
Again, an association doesn’t prove cause and effect. So this study doesn't show that too little or too much sleep was deadly.
Go to Bed
All these conditions can be related to sleep in one way or another. In many cases, the effects are only seen after years of sleep loss. But in others, like delayed reaction times, glucose load, depression, headaches, and HORMONE balances, can be affected after one night of sleeping six hours or less.
But what about those people who say they can easily get by on five hours? It’s actually “the opinion of sleep doctors that there are some people who only need five hours,” Shives says, “but that’s 5% of the population or fewer. And you still wonder if it’s best for them, given the research.”
The best way to figure out how much sleep you need is to take a vacation. “Climb into bed when you’re sleepy and get up when you want,” Quan says. “The goal is that you don’t feel sleepy during the daytime and you’re functioning well.”