Can We Get Away With Sleeping Under 7 Hours?

Spoiler: no

How bad is it?

Researchers (Dr. Kathryn McAuliffe et al.) looked at data from thousands of Americans, and found that sleeping fewer than seven hours per night is strongly associated with shorter life expectancy, with a stronger link than diet quality, physical activity, or social isolation.

The only thing that scored worse was smoking. It’s that bad.

This was very consistent too; the relationship between sleep duration and life expectancy appeared year after year and all across the US.

To put it un numbers, sleeping insufficiently (defined for the study as: under 7 hours/night) was associated with up to 9 years lower life expectancy.

For the more visually inclined, here’s an example graph from the paper ← this one’s for the state of Oregon

And yes, that association holds even when controlling for other mortality predictors, so it’s not merely some manner of “unhealthy disabled poor people sleep less”, even though that will also be the case too:

❝We find that at the United States county level, higher sleep insufficiency was significantly associated with lower life expectancy and with changes in life expectancy across years even when controlling for notable mortality predictors. These data highlight the importance of sleep to health and suggest that sleep could be a modifiable behavior for improved longevity in the United States.

The magnitude of the data included in this analysis is vast, including all 3143 counties in the United States, strengthening the results of this analysis. Moreover, because data were collected in counties across the United States, our outcomes represent a wide range of demographics and behaviors, further strengthening the generalizability and robustness of our findings.❞

Read in full: Sleep insufficiency and life expectancy at the state-county level in the United States, 2019–2025

This is important, because when people make plans for improving their health, it is nearly always a matter of focusing on diet and exercise.

And yes, those things are very important! But they are nothing without good sleep.

So, how to do better?

We’ve written a bit about this before, including:

Why You Probably Need More Sleep ← a lot of people mistake getting 6 hours sleep per night for only needing 6 hours sleep per night. Sure, you may still be alive after regularly getting 6 hours, but (unless you have a rare mutation of the ADRB1 gene) it will be causing harm, and yes, that includes later in life; we don’t stop needing so much sleep, even if we stop getting it.

It’s also noteworthy that sleep-deprived people usually underestimate how sleep-deprived they are. This is for the same reason as why drunk people usually underestimate how drunk they are—to put it in words that go for both situations: a cognitively impaired person lacks the cognitive function to realize how cognitively impaired they are. Here’s the science on that: How Sleep-Deprived Are You, Really?

There are more considerations, though, for example:

How Regularity Of Sleep Can Be Even More Important Than Duration ← here’s why you should still get up at the same regular (and ideally, early) hour, even if you didn’t sleep well

Early Bird Or Night Owl? Genes vs Environment ← and here’s why that regular hour should ideally be early, even if it’s not your genetic predisposition to be a “morning lark”; see also the study linked there that mentions “Gene distinguishes early birds from night owls and helps predict time of death”

Some sleep aids can help, but many are harmful and/or do not really work as such; here’s a rundown of examples of those:

Safe Effective Sleep Aids For Seniors?

And when it comes to napping, timing is everything:

How To Nap Like A Pro (No More “Sleep Hangovers”!)

Want to learn more?

For a much more in-depth treatment of the topic, you might:

Why We Sleep – by Dr Matthew Walker

Basically, if you will read only one book on sleep, that’s the book.

Sweet dreams!