Do You Really Need Less Sleep As You Age?
There’s no doubt that kids need more sleep than adults. Their growing bodies and brains burn through a lot of energy, and adequate rest and recovery are essential for proper development. That’s why the National Sleep Foundation recommends that teens get eight to ten hours of sleep a night, while younger kids require more.
But what about adults? It’s common for people to sleep fewer hours in middle age than during their 20s or 30s—and to report feeling fine. But does a person’s sleep requirements diminish with age? “No,” says Dr. Leila Kheirandish-Gozal, director of clinical sleep research at the University of Chicago. “The amount of sleep needed doesn’t change, but the perception of sleep changes.”
The human body is capable of adaptation, Kheirandish-Gozal explains. If you move to a colder climate, you’ll eventually get used to it. And, in the same way, a person’s body and brain can grow accustomed to operating without adequate sleep. This may not produce any noticeable issues in the short term. But over time, Kheirandish-Gozal says, insufficient sleep can mess with a person’s metabolism, mood, memory and heart function—therefore increasing his risk for obesity, diabetes, forgetfulness and heart disease, to name just a few of the many conditions linked to chronic poor sleep.
Another factor to consider: When it comes to sleep, need and ability are two different things. “It’s pretty clear that sleep ability decreases with age,” says Michael Grandner, director of the Sleep and Health Research Center at the University of Arizona College of Medicine. Many older adults assume that their inability to sleep soundly or for extended periods is a sign that they don’t need as much rest. But that’s probably not true, Grandner says. (Some older adults also struggle to perform physical activity, but that doesn’t mean exercise is any less important.)
So how much sleep do middle-aged and older adults really need for optimal health? That’s tricky. “We say, on average, try to get seven or eight, but inevitably you’ll have people who need more or less than that,” Grandner says.
There are plenty of scientific challenges involved with measuring “adequate” sleep. For one thing, we all tend to be poor judges of our own sleepiness levels. “You ask people how well-rested they are, and they have no idea,” Grandner says. “People say they’re totally fine, but then we look at objective performance measures—like reaction or focus—and we see pretty dramatic declines.”
Also, in order to produce measurable short-term effects, Grandner says researchers need to severely reduce a person’s sleep—knocking them down to five hours or less per night, which pretty much everyone agrees is too little sleep. But when you’re comparing six or 6.5 hours to 7.5 or eight, short-term harms are more difficult to tease out.