The common consensus is that most adults should get 8 hours of sleep a night.

However, sleep needs are highly variable, with some people needing more to function properly, and some gaining little benefit past just a few hours. I'm trying to learn more about the statistics here.

I'd imagine sleep needs would fit a normal distribution, with a median of around 8 hours and a standard deviation of around an hour. The empirical rule would then put 68% of adults in the 7-9 hour range, 95% in the 6-10 hour range, and 99.7% in the 5-11 hour range, but that's just a guess.

Has this distribution been studied, and where?

  • 1
    One of the challenges here is a standard operational definition of how much sleep anyone needs. I'm not current on the sleep literature, but I don't believe it is particularly straightforward. Some groups may have approached it from a disease risk perspective, others from the perspective of optimal cognitive function, etc.
    – De Novo
    Feb 18, 2019 at 23:59
  • @DeNovo raises a good point. I think you need to clarify how you define "need" for purposes of this question.
    – Carey Gregory
    Feb 19, 2019 at 0:07
  • @CareyGregory I'd agree. It's not obvious though what the best criteria would be for that clarification. What I'm really looking for is optimal health or at least non deteriorating health, but neither of those criteria are particularly easy to quantify Feb 19, 2019 at 0:11

2 Answers 2


Many well-done newer studies are supporting the theory that quality trumps quantity when it comes to sleep. This excellent article at lifehack.org lists 12 good sources, including “two studies (which) assessed how sleep quality and quantity affected college students’ health and well-being. The studies concluded that sleep quality was a better predictor for a healthy and happy life and improved well-being than sleep quantity.”

For those who still want it boiled down to a number, here are the numbers the National Sleep Foundation updated in 2015:https://www.sleepfoundation.org/press-release/national-sleep-foundation-recommends-new-sleep-times link: https://www.sleepfoundation.org/press-release/national-sleep-foundation-recommends-new-sleep-times


If you are aged between 26 to 64 year age, you need minimum 7-9 hours of sleep (other factors like your physical work, stress plays extra role).

If you are doing more physical hard work, you might need 8-9hrs of sleep, while with desk job, you are with 7hrs of sleep as well.

You can check the National Sleep Foundation data as below for age wise sleeping hours required. enter image description here



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