Harvard professor ‘debunks the myth’ that you need eight hours of sleep

It’s one of the most common tips for a good night’s rest: get at least eight hours of sleep a night. But a professor at Harvard University claims that eight is not the magic number.

Dr. Daniel Lieberman, from the university’s Department of Human Evolutionary Biology, said “people do better if they get seven hours of sleep.”

‘This idea that you need eight hours of sleep it’s been around for a long time, basically since the industrial revolution,’ he said last week on an episode of the Diary of a CEO podcast.

Dr. Lieberman used populations that do not have manufactured light (electricity, telephones, televisions) as an example. Research has shown that those who don’t spend all day on their phones or staring at screens don’t need as much sleep.

‘Colleagues in my field, in evolutionary medicine, have put sensors on people who don’t have all the things that tell us they have destroyed sleep. They tell us that the television, the lights and our phones, and all these things, keep us from sleeping,” he said.

‘When you put sensors on people who don’t have electricity and they don’t have televisions and they don’t have phones and they don’t have any of these gadgets, it turns out they sleep like six or seven hours a night, and they don’t nap.

‘So this idea that natural human beings sleep eight hours a night is just nonsense. It’s just not true.

Limiting screen time may make you need less sleep in the long run, he said.

The recommendation falls on the low end of the Centers for Disease Control and Prevention (CDC) guidelines, which state that all Americans should get seven to nine hours of sleep each night.

Children ages 6 to 12 need nine to 12 hours a night, while teens should get eight to 10 hours of sleep, according to the agency.

However, a growing body of research supports Dr. Lieberman’s theory.

A study published last year in the journal Nature Aging found that seven hours is the ideal amount for middle-aged and older adults.

The research suggested that anything above or below that amount was associated with cognitive difficulties such as the inability to remember, learn new things, concentrate, solve problems and make decisions.

Additionally, those who did not receive seven hours were more likely to have symptoms of depression and anxiety.

“People do better if they get seven hours of sleep, and yet we’re told that if you don’t get eight hours, something is wrong,” said Dr. Lieberman.

According to CDC figures, one-third of Americans ages 18 to 64 don’t get enough sleep—at least seven hours a night.

This drops to 26 percent when adults are over 65, but still more than a quarter of adults don’t get enough sleep.

Lack of sleep has consistently been linked to chronic health problems, including heart disease, kidney disease, high blood pressure, diabetes, stroke, obesity, and depression.

However, there are some caveats about the seven hour rule.

“People who are sick may get more sleep, so there are some biases that creep into the way you analyze the data, but basically it turns out that seven is, for most people, optimal,” said Dr. Lieberman.

Certain populations are also more likely to have different sleep schedules. While a teenager may sleep in on the weekends, older adults may get less rest or more interrupted sleep.

For a restful night’s sleep, the American Academy of Sleep Medicine recommends going to bed at the same time every night and getting up at the same time every morning, even on weekends.