Harvard Professor Bashes Idea That We Need 8 Hours of Sleep at Night

“This idea that natural human beings sleep eight hours a night is just nonsense,” Dr. Daniel E. Lieberman recently claimed, on the Diary of a CEO podcast.

Needing 8 hours of sleep has become common sleep knowledge, but is this actually true? While this might seem like a bold claim, Lieberman’s explanation makes sense.

Lieberman is a Harvard Professor, best known for his research on human evolution, paleoanthropology, evolutionary medicine, and exercise. Long story short, he’s very smart.

“This idea that you need eight hours of sleep has been around for a long time, basically since the industrial revolution,” Lieberman tells host Steven Bartlett.

He explains that we’ve been told our phones, televisions, and lights are things that prevent us from sleep, jokingly saying, “Edison destroyed sleep, right?”

However, his colleagues in evolutionary medicine have done research on people who don’t have these sleep preventing gadgets and these people sleep six or seven hours a night, with no naps.

“So, this idea that natural human beings sleep eight hours a night is just nonsense, it’s just not true,” Lieberman explains.

Instead of eight hours of sleep being the standard amount of sleep needed, Lieberman believes seven hours of sleep should be recommended:

“When you start looking at the data, seven hours, if you actually look at graphs of how many hours a night you sleep on the X axis and some outcome like cardiovascular disease or how likely you are to die, it’s kind of a U-shaped curve. People who don’t get much sleep are in trouble, but the bottom of that curve is pretty much always like seven hours.”

Because of this data, Lieberman continues saying, “People actually do better if they sleep for seven hours, and yet we’re told that if you don’t sleep for eight hours there’s something wrong.”

Liberman’s claim isn’t completely false. The suggested amount of sleep from national organizations including the CDC, National Health Institutes, and the Mayo Clinic all include ranges of hours depending on age. For adults it’s recommended seven or more hours per night, with some specifically stating seven to nine hours per night.

Like most things, there’s a level of complexity to how much sleep you need. Lieberman does note this by pointing out you’ll need to sleep more if you’re sick and there’s biases that can creep into how you analyze the date, but overall believes seven hours is optimal for most people.

Dr. Shelby Harris, Sleepopolis’ director of sleep health, agrees that eight hours isn’t the definitive number for everyone, “The number of hours of sleep you’ll need ranges from 7-9 hours and could even be as little as 6 for some people.”

Harris explains that the key to good sleep is consistency. As for the sleep distractions that Lieberman points out, Harris agrees there are more distractions today, but it’s more than just the use of electronics before bed. “We also live in a society that’s 24/7 and there’s just little demarcation between work and play/rest time. As a result, our brains are always on.”

The amount of sleep you need may not be the same as your partner, friends, or other family members, after all, there’s a recommended range for a reason. Overall the goal is to get good quality sleep, so if you’re getting that with seven or eight hours of sleep, just keep doing what you’re doing.