|November 29, 2023

How Much Sleep Is Enough? How Much Is Too Much?

By Dave Asprey
Reviewed for Scientific Accuracy

How Much Sleep Is Enough? How Much Is Too Much?

  • Getting eight hours of sleep per night is old news.
  • Research from the University of California, San Diego suggests that sleeping five hours per night is slightly safer than sleeping eight.
  • These findings support what I’ve been saying for years: sleep quality matters more than sleep quantity.
    Get Bulletproof tips to sleep better, faster, starting tonight.

You’ve heard it before: “Everyone needs eight hours of sleep per night.”

A study out of the University of California, San Diego paints a different story. The 2010 paper suggests the secret to a long life has to do with getting just enough sleep, not necessarily eight hours of sleep per night.[1] The study looked at 1.1 million people’s sleep patterns over the course of six years, tracking the amount of sleep each subject averaged alongside their longevity.

Its major finding: Sleeping as little as five hours per night can be better for you than sleeping eight.

How much sleep do you really need?

Woman sleeping face-down on bed

The study was run by , MD, a professor of psychiatry specializing in sleep research and aging. Researchers didn’t find any statistical health-related reason to sleep longer than six and a half hours per night.

He used data from the that shows sleeping for about five hours per night is slightly safer than sleeping eight. In this case, we’ll go ahead and define “safer” as “not dying.”

The UCSD study’s data is impressive. The data is from 1982-1988 because it took years to input the data and analyze it. It covers 1.1 million participants, and it is the first large-scale population study that correlates sleep with longevity while taking into account things like age, diet, exercise, health problems and smoking.
I’m not sure where the sleep-8-hours-per-night myth came from, but it’s totally wrong. You can file it away under old information, along with the eat-fewer-calories-to-lose-weight myth.

Mental and physical benefits of sleep

Man wearing blue shirt jogging outside

Doctors, health experts and athletes agree that getting consistent, quality sleep is critical. Here are just a few studies that prove just that:

The mental benefits

  • Improves your ability to learn new motor skills by 20 percent[2]
  • Increases your ability to gain new insight into complex problems by 50 percent[3]
  • Enhances well-being and mood[4]

The physical benefits

  • Good sleep promotes skin health and a youthful appearance.[5]
  • Sleep increases athletic performance.[6]
  • Sleep helps regulate your hormones and may even increase testosterone levels.[7] [8]

If sleep is so awesome, why get less of it? The short answer is: It’s the quality of your sleep that matters, not the quantity.

How to hack your sleep

Bottle of Bulletproof Sleep Mode on white bed

If you find that you need a ton of sleep, your body is trying to tell you something. Stress, over-exercising and diet are all common reasons you might find yourself feeling so fatigued. That’s where biohacking comes to the rescue.

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