Imagine what else you could do with the hours you spend unconscious each night. Oh, the things you could accomplish!
But if you’re trying to claw back more of your personal time, sacrificing sleep is not where to start. The American Academy of Sleep Medicine and the Sleep Research Society both recommend a minimum of seven hours a night to maintain optimal health. If you regularly sleep less than that, “you’re going to experience physical, psychological, and social consequences,” says Joe Dzierzewski, vice president of research and scientific affairs at the National Sleep Foundation.
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There are two exceptions to this advice. Older adults typically need less sleep than people who are younger, says Lynelle Schneeberg, a sleep psychologist and assistant professor of psychiatry at Yale Medicine. For instance, someone who slept eight hours a night in their 40s might be able to function well with 6.5 hours a night in their 70s. Older people produce less of the sleep-promoting hormone melatonin, and they tend to have more medical conditions that can interfere with sleep.
In addition, a very small number of people have a genetic mutation that allows them to function on less than 6.5 hours of sleep per night with no apparent consequences to their health. This genetic mutation is quite rare, with experts estimating that it only affects around one in 25,000 people.
But for everyone else, here’s the bottom line on how low you can go: seven hours is the minimum for your regular sleep schedule, anything between five and seven hours isn’t great but will do if it’s just a night or two, and anything less than five hours—for any length of time—can have serious consequences.
Surviving versus thriving
Most sleep experts recommend getting somewhere between seven and nine hours of sleep per night. But this isn’t always achievable. Perhaps you have a newborn who won’t sleep, you’re grieving the loss of a loved one, or you’re a medical resident working 80 hours a week.
If special circumstances aren’t allowing you to sleep as much as you need to, Schneeberg says, at least try to get 5.5 to six hours each night. “That’s not what I want people to strive for,” she says, but it will allow you to log some deep sleep.
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Although you might be able to survive with less than seven hours of sleep a night in the short-term, you definitely won’t be thriving, especially if you keep it up for a while. “Can you compensate on a short-term basis for an occasional night of poor sleep? Yes, you can,” Dzierzewski says. “But if you consistently neglect your sleep health, will it eventually catch up to you? More than likely.”
cascade of negative effects from too little sleep
Many people don’t prioritize their sleep because a night or two of poor sleep doesn’t lead to any immediate or dire consequences, Dzierzewski says. But once people get less than about five hours of sleep per night, they start to experience clear detriments to their physical health, says Aric Prather, a sleep scientist and professor in the department of psychiatry and behavioral sciences at the University of California, San Francisco.
A day of less-than-adequate rest can lead to poor mood, concentration, and attention, along with greater susceptibility to illness and riskier driving, Dzierzewski says. Short-term sleep loss can also lead you to crave foods that are higher in fat and sugar because your body produces extra cortisol, the stress hormone, when you’re sleep-deprived, says Michael Breus, a clinical psychologist and sleep medicine specialist in Hermosa Beach, Calif.
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A prime example of the consequences of short-term sleep loss: Motor-vehicle fatalities rise by 6% in the workweek following Daylight Saving Time in the spring, according to a 2020 study published in the journal Current Biology. (The authors believe this is due to a combination of sleep loss and driving to work in the dark.) Another study found a 24% increase in heart attacks on the Monday after Daylight Saving Time, and a 21% decrease once the clocks turn back in the fall.
Chronic sleep deprivation over weeks, months, or years can lead to a host of problems, including increased insulin resistance, increased inflammation in the body, and high blood pressure, Prather says. Long-term sleep deprivation can also increase someone’s chances of having a heart attack or stroke. Early research has even begun looking at whether people who don’t get enough sleep for a long time are at a higher risk of developing neurodegenerative diseases like Alzheimer’s, says Prather, who wrote The Sleep Prescription. “There are some devastating things that can happen when people don’t get the sleep they need for a sustained period of time,” he says.
Quality counts, too
When it comes to getting good shuteye, quality matters just as much as quantity. “Sleep health is multidimensional,” Dzierzewski says. “It’s made up of more than just duration.”
How many times you hit the snooze button, how long it takes you to fall asleep, how often you wake up at night, and how rested you feel in the morning are all good indicators of whether or not you’re getting good quality sleep, Breus says. “You can get eight hours of really [poor] sleep, and it’s not going to do you a whole lot of good,” he says.
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Sleep continuity, or sleeping most of the night without any wakeups, is of particular importance, Prather says. “If you got seven hours of sleep, but it took 10 hours to get it because there were all of these awakenings in the middle of the night, it just doesn’t feel as high quality, and it impacts how you feel during the day.”
Figuring out your genetic chronotype can be a good way to ensure you’re getting high-quality sleep. Your chronotype is when you are biologically programmed to sleep, Breus says. (Think early birds and night owls.) Sleeping according to your chronotype can help you get more restorative sleep, Breus says.
Short sleep is nothing to brag about
We often hear stories of people—famous and otherwise—who function on very little sleep. Former president Barack Obama reportedly only slept about five hours per night during his presidency. Dwayne “The Rock” Johnson once said he only sleeps three to five hours per night. And we all know at least one family member or friend who swears they only need five or six hours of sleep a night.
Don’t believe them. “Functioning on less than seven hours of sleep on a routine basis is not a badge of honor,” Dzierzewski says. “I don’t think it’s anything that anyone should be proud of… It would be like someone saying, ‘I’m able to maintain a healthy weight when all I do is eat chocolate all day.’” If you’re looking for more hours in your day, start trimming something else besides your sleep.
