That old wisdom about getting a solid eight hours of sleep per night? Not exactly true. In fact, the amount of sleep you need is totally unique to you—and may not necessarily be eight straight hours. According to a wide variety of studies, the average optimal amount of sleep across the whole population is actually closer to seven hours nightly.

Based on the rash of recent findings, the American Academy of Sleep Medicine (AASM), Sleep Research Society and Centers for Disease Control are convening a conference to determine the right amount for sleep for best health, says Dr. Nathaniel Watson, MD and president-elect of the AASM. Until then, there are a few ways to figure out your personal needs with some help from the pros.

What Science Says About Sleep

“Generally speaking, the proper amount of sleep is the amount that allows the individual to wake refreshed and to remain alert throughout the day without the need for caffeine or other stimulants,” says Dr. Watson. “At the moment we recommend seven to nine hours per night,” he adds.

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Studies provide a range of much more colorful answers, though. One frequently cited 20-year study completed in 2002 analyzed self-reported sleep logs and found that those individuals who were asleep for seven hours per night lived longer than those who slept eight hours or more. Of course, correlation doesn’t necessarily mean causation. According to Dr. Watson, “Long sleep may be a surrogate marker of poor health.” In other words, study subjects’ poor health may be what’s causing their excessive bedtime routine, not vice versa.

Another more recent study, which focused on cognitive abilities in women 70 or older, reached a familiar conclusion: Sleeping nine hours or more was just as harmful as sleeping five or less. A study of a broader section of the population, based on data from Luminosity, also found that cognitive performance peaked at about seven hours—but dropped off more slowly after seven hours than the former research suggests.

Similarly, scientists have found that for troubled sleepers (including some elderly populations and those suffering from insomnia), it can make sense to restrict sleep to less than seven-and-a-half hours per night. “Conversely, spending excessive time in bed can elicit daytime lethargy and exacerbate sleep fragmentation,” they state.

All that said, it’s still hard to generalize the optimal amount of zzz’s. “It’s important we note that no study will tell an individual exactly how much sleep they personally need—we can’t take these studies and make individual recommendations,” says Dr. Watson. Keep in mind that much of the scientific research involved self-reported data, considered narrow populations or examined sleep patterns of those with known sleep disorders like insomnia.

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Figuring Out Your Sleep Needs

Dr. Watson suggests using an upcoming vacation to figure out the correct amount of sleep for you. “Try going to bed around the same time each night and waking up without an alarm clock for several days.” After a week of regular bedtimes and unlimited sleeping in, you should land on your ideal amount of sleep, which is likely to fall in the seven to nine hour range. (It’s important to keep in mind that this kind of sleep experimentation doesn’t necessarily work on a weekend. Dr. Watson points out, “The first few nights…you may sleep eight to nine hours if you’ve been extra tired or sleep deprived from the week.”)

However, if you’re a long snoozer (and you don’t experience insomnia or any other bedtime disorders), you shouldn’t stress the potential negatives of over-sleeping. “I would not recommend that anyone achieving eight or nine hours of sleep reduce the amount they’re currently getting,” warns Dr. Watson, especially if you’re functioning well throughout the day with lots of energy and little lethargy.

Athletes who put high demands on their bodies should also tune in closely. Active individuals will need extra zzz’s since functions like tissue repair and protein synthesis (key to restoring the body after a taxing workout) mostly take place during sleep.

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Changing Your Patterns

Wishing you needed less time out cold? Unfortunately, your bedtime necessities are hard to change. “There is no way to decrease the amount of sleep you need—this is largely determined by genetics,” says Dr. Watson. If you feel the most on your game after eight and a half hours of sleep, that’s just the reality.

The best way to get the most out of your zzz’s—especially important when it comes to recovery and training—is to simply get better sleep. Avoid alcohol whenever possible as it can throw off your routine hours. Also try to steer clear of caffeine or other sleep-disrupting meds at least six hours before your head plans to hit the pillow. Lastly, know that sticking to a regular sleep-wake schedule is the best way to avoid feeling sluggish.

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