Is 6 Hours of Sleep Enough?

Two things are true at once here, and holding both is the whole point of this page.

The recommendation

In 2015, the American Academy of Sleep Medicine and the Sleep Research Society published a joint consensus statement. Its recommendation:

"Adults should sleep 7 or more hours per night on a regular basis to promote optimal health."

And conversely, on the other side of the line:

"Sleeping less than 7 hours per night on a regular basis is associated with adverse health outcomes, including weight gain and obesity, diabetes, hypertension, heart disease and stroke, depression, and increased risk of death."

The statement also links inadequate sleep with "impaired immune function, increased pain, impaired performance, increased errors, and greater risk of accidents."1

So, on the direct question: six hours on a regular basis sits below what the specialty bodies recommend.

Two qualifiers are worth holding onto. The operative phrase is "on a regular basis" — this concerns habitual duration, not what happened last Tuesday. And these are associations across populations, not a prediction about any individual. Sleep needs vary, because everyone has different needs.

Eight hours is not the number

This is worth stating plainly because this belief could cause considerable harm.

The recommendation is a floor of seven, but not a target of eight. Nowhere in the consensus statement does eight appear as a requirement. Yet "you need eight hours" remains one of the most firmly held beliefs about sleep. For people who sleep poorly, it functions as a nightly scoreboard they miss every day.

Worrying about sleep is itself a symptom in the diagnostic criteria for insomnia, and the gap between a person's actual sleep and an imaginary eight-hour requirement contributes directly to that worry.2

Where this gets complicated

If you have insomnia, you may already be thinking: so I should be getting more sleep, and the treatment tells me to spend less time in bed?

Both are right, and the reason is that time in bed and time asleep are different things.

Let's say you are currently sleeping six hours. There are two different paths to try and get to 7 hours of sleep as your new normal.

Route one: spend more time in bed. This seems like the logical path. Go to bed at ten instead of eleven; lie in at the weekend. In practice, this rarely produces more sleep. It turns into more time lying awake, which dilutes sleep pressure, makes the sleep you do get lighter, and adds extra hours each night in bed that are associated with being awake.

Route two: increase your sleep pressure so that when you get into bed, you are ready to fall asleep. One way to do this is to temporarily narrow the window when you are in bed so that nearly all of the time you spend in bed is spent asleep, then extend it gradually as that proportion improves. This is called sleep restriction therapy, and it is one of the core components of the treatment for chronic insomnia.34 You start by spending less time in bed to increase sleep pressure, which helps you fall asleep faster when you are in bed, and helps your mind associate the bed with being asleep instead of being awake.

It may seem counterintuitive at first — spend less time in bed to sleep more — but this is a technique that has been proven to work, and it helps people with chronic insomnia learn to sleep well again.