These “short sleepers” don’t necessarily do it by choice—they’re genetically programmed to require less shut-eye.
At first, Brad Johnson thought his inability to sleep as much as other people meant there was something wrong with him. Despite being an energetic and focused child, and later a high-achieving adult, Johnson carried this worry in the back of his mind.
“I just physically cannot sleep like other people. And everything you read says you’d have to have seven, eight, nine hours of sleep, or you’re staring serious health conditions in the face, and you can’t ever be as productive,” Johnson, 65, tells Popular Mechanics. For as long as he can remember, he has slept only between four and six hours a night. Since childhood, the same was true of four of his seven siblings and his father. For them, six hours of sleep is the equivalent of eight or nine hours for most people. “Less than [four hours], and I have the same problems everyone else does if they’re sleep-deprived,” he explains.
As time went on, Johnson did well at college, went on to hold top leadership positions at Lands’ End and REI, became very active with his church, and had eight children with his wife. Amidst this very busy lifestyle, he still wondered why he felt great after just six hours of sleep, and why he never needed an alarm clock to awake refreshed every morning.
It wasn’t until 2005 that Johnson started to find some answers. He decided to join a sleep study to identify people who do remarkably well on very little sleep. A few years later, he participated in a follow-up sleep study because his blood showed specific gene mutations that most people don’t have. During the studies, Johnson answered extensive questionnaires about his sleep habits and health, and researchers monitored his daily sleep and activity levels for eight days.
Researcher Ying-Hui Fu of the Weill Institute for Neurosciences at the University of California, San Francisco studies sleep behaviors and circadian rhythms—the body’s natural clock for sleeping. She and her team found in 2009 that the genes of so-called “short sleepers” have certain mutations that are responsible for super-efficient sleep. At this point, her team had identified five mutations in three genes that control how much shut-eye people need, but Fu suspects there are more genes involved.
Sleep governs your cognitive and neurological functions, like memory, thinking, learning, moving, and feeling energetic. Sleeping many hours does not necessarily correlate with getting quality sleep, however. The more efficient your sleep is, the less you need. And that’s a hallmark of short sleepers, who need about half as much sleep as the vast majority, but perform as well as regular sleepers, Fu explains to Popular Mechanics.
While it’s a rare individual who is genetically wired to sleep fewer hours in a day, all of the people she and her team have identified as short sleepers have several things in common. They tend to live longer and healthier lives, both physically and mentally. These people are truly lucky, her research finds, because they seem to share some awesome characteristics:
“These short sleepers not only need less sleep, but while they’re awake—for 18 to 20 hours— they are more active than typical sleepers. With all that extra time, they tend to be multitaskers,” Fu says. That means they may have two jobs, or be studying while working and having hobbies, for example. They don’t tend to be idle, she says.
Short sleepers also seem to have less disease than regular sleepers. Health problems like diabetes, heart disease, and other illnesses don’t begin to develop until much later in a short sleeper’s life. Even the 60- to 80-year-old sleepers in Fu’s studies are healthy and active. For example, one study participant who’s almost 80 years old was recently training for a triathlon. Others can exercise for a long time without pain. They also deal with stress better than regular sleepers and are “very optimistic, cheerful, and resilient,” she says. They also share some other unusual traits, including better memories, higher pain tolerance, and lack of jet lag, she adds. “Their bodies’ [function] at 100 percent or close to that every day,” Fu says. One of the study subjects had an ability to remember everything and never needed to take notes in class. Another knows 13 languages. Some others can exercise for long periods without pain.
Sleeping Late, Rising Early
Sleep is our body’s first line of defense against poor health. “When we are sleeping, our body is working very hard to help us maintain our health—to remove toxins, to remove waste products, to repair damages, to do all kinds of things, so that our body can maintain the health that we should have,” explains Fu. “So let’s say there are ten things our body needs to do when we sleep. And what takes eight hours for most of us, for these [short sleepers] it only takes four to six hours. Why?”
That’s the ultimate question for Fu and her fellow researchers.
In her earlier sleep research, Fu and her team had been looking at people who were “morning larks,” those who were going to bed early and getting up early. Along the way, they discovered a gene mutation in some of the people in the morning lark study. It turned out these particular folks didn’t go to sleep early, but still awoke super early, Fu says.
After this discovery, Fu and her team started recruiting people who fit the profile of sleeping late and rising early. “We got thousands of emails from people saying ‘I’m like that,’ or ‘I know somebody like that,’” Fu says. While there were many in the group who slept less, only a small percentage of them—just over 100 people, Johnson included—emerged as true short sleepers.
Once the researchers confirmed that the characteristic gene mutation was common to all of the short sleepers, they wanted to know how it affected the brain. They turned to mice to gain a better understanding of the brain neurocircuitry involved in sleep. “Mice who carry the same mutation also sleep less. At that point, we said, we think this is real,” Fu says.
Fu studied the brains of mice with short-sleep gene mutations, looking for “unique neurocircuits for sleep duration and efficiency” and specific patterns of brain activity during sleep. While she has found some common brain mechanisms, future studies are necessary to explain how the genes regulate human brain function, she says. But observing the same gene mutations and behaviors in healthy mice bolstered Fu’s conclusion that it is possible for humans to sleep four to six hours and stay healthy, as well as function perfectly.
What It’s Like to Be a Short Sleeper
One of the common experiences of short sleepers is higher-than-usual pain tolerance. Johnson has direct experience with this aspect. Both his knees need to be replaced, but they don’t bother him unless he jumps or runs, so he’s put off the procedure, much to his doctor’s astonishment, he says. He went through the trouble of his first colonoscopy without anesthesia, because he had forgotten to arrange for someone to drive him home afterward. “It was uncomfortable. It was painful. But it was something I could do,” he says.
It’s not surprising that Johnson and some of his immediate family members have the same short sleep needs, says Fu, since a genetic component is an important part of sleep behavior. Still, it appears to be a rare trait, she says. None of Johnson’s kids are short sleepers, and most of his siblings’ children aren’t either.
Johnson thinks of his short-sleep genes as a gift. They are responsible for his ability to accomplish much more than he otherwise would have, including giving back to those in need through his church, he says. He feels lucky “for a chance to give back in a way that I couldn’t otherwise. And in that way, that gift is very meaningful. Because I think in giving back and helping others, that’s where we find great joy and fulfillment in life.”
So why do people like Johnson have this mutation in the first place?
Fu doesn’t know, but she imagines it may have something to do with more hours of bright light since the advent of electric lights in the home. Maybe it’s an environmental reaction to going to bed later. It’s interesting to speculate, but there’s no way to prove it at this point, she admits.
What’s more important is planning more studies to understand what short sleepers’ brains actually do during sleep. For example, is there anything different about their dreaming, known as REM cycles? Fu hopes this understanding could lead to therapies that help everybody achieve more efficient sleep and lead healthier, longer lives.