It’s classic health advice, right up there with eat your fruits and veggies and break a sweat on the regular: Get eight hours of sleep a night. But what if it’s not true?
A Wall Street Journal article caused a stir this week by asking if seven hours might just be the new eight: “Sleep scientists say new guidelines are needed to take into account an abundance of recent research in the field and to reflect that Americans are on average sleeping less than they did in the past. Several sleep studies have found that seven hours is the optimal amount of sleep—not eight, as was long believed—when it comes to certain cognitive and health markers, although many doctors question that conclusion.”
So if you’re a regular eight-hour sleeper, should you start cutting that short for the sake of your health? Probably not.
“There’s no strong evidence that someone sleeping eight [hours] and feeling fine should switch to seven,” says Michael Grandner, Ph.D., a psychiatry instructor and member of the Center for Sleep and Circadian Neurobiology at the Perelman School of Medicine at the University of Pennsylvania. “There’s very little evidence to suggest that seven is actually better than eight.”
Instead, Grandner says the article should serve as a reminder that there’s no “magic” number when it comes to sleep. In fact, ideal sleep target numbers are highly personal.
The average ideal amount of sleep seems to hover somewhere around seven to eight hours. A very small percentage of people are so-called short sleepers who get by on five or six a night (estimates put the number at about 1 to 3 percent) without ill health effects and another small group are so-called long sleepers who need to bank more sleep to feel their best. The rest of us fall somewhere in the middle.
“The average tells us about a population, it doesn’t tell us about what an individual should do,” Grandner says. “It doesn’t predict things perfectly. … Nobody has 2.1 children, even though that’s the average.”
That said, if you’re really struggling to fall asleep at night, you might want to reconsider your shut-eye target number, says W. Christopher Winter, M.D., medical director of the Martha Jefferson Hospital Sleep Medicine Center in Charlottesville, Virginia. Think about it, he explains: Would you go to dinner at four o’clock if you weren’t hungry until six? “Hopefully this research gives people the freedom to break this eight-hour shackle,” Winter says. When trying out a new schedule, he recommends sticking to regular hours (a consistent wake time is most important) and sticking with it for a few weeks to evaluate how you feel.
One group who should give serious consideration to the findings is the 40 percent of Americans who typically clock six or fewer hours of sleep a night―research has consistently linked short sleep with serious health effects, including obesity, heart disease, and diabetes. The good news for them is that seven hours might be a less intimidating goal than eight, says M. Safwan Badr, M.D., immediate past president of the American Academy of Sleep Medicine and chief of the division of pulmonary, critical care, and sleep medicine at Wayne State University School of Medicine in Detroit. “If you’re unable to make it to eight hours, make it seven at least,” he says.
While Badr says the average healthy person “[doesn’t] have to worry about OD’ing on sleep,” if you find yourself regularly craving nine, ten, or more hours at night, Winter recommends seeing a doctor to rule out underlying health problems, such as sleep apnea, restless legs syndrome or narcolepsy.
So how, exactly, can you determine how much sleep is enough for you? Grandner offers these tips:
1. No matter how bored you are in a meeting, if you have trouble keeping your eyes open, it’s a red flag you need more rest.
2. If you wake up feeling like you just ran a marathon―and the feeling doesn’t go away after 10 to 20 minutes―that’s a sign you’re sleep-deprived (or that your z’s are poor quality).
3. Do you pass out as soon as your head hits the pillow? It’s time to bank more sleep―your body is starving for it. On the other hand, if it takes you more than a half hour to fall asleep, or if you wake up in the middle of the night and it takes you that long to drift back to sleep, that might be a sign of insomnia.