science of us

What It Actually Means to Get a Good Night’s Sleep, by the Numbers

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“Get a good night’s sleep” is one of those pieces of health advice that falls into the same category as “everything in moderation” or “get enough exercise” — you know in a vague, general sense that it’s a good idea, but it’s too low on specifics to actually be an action item. Is there a certain number of hours that separates a good night’s sleep from a bad one? Or is it more about how much you toss and turn, or what time you go to bed, or something else altogether?

“In the past, we defined sleep by its negative outcomes including sleep dissatisfaction,” Maurice Ohayon, the director of Stanford Sleep Epidemiology Research Center, explained in a recent statement — that is, a good night’s sleep was just one that didn’t inspire any complaints. But “clearly, this is not the whole story.”

So Ohayon, along with several other sleep experts, reviewed more than 200 previously published sleep studies in an attempt to define more concretely what sort of sleep people should aspire to each night. In a new paper in Sleep Health, a journal run by the National Sleep Foundation, they outlined the four criteria they landed on. Here, according to the report, is how to know if the shut-eye you’re getting is actually quality sleep:

1. You take half an hour or less to fall asleep.

2. You wake up no more than once per night.

3. If you do wake up in the middle of the night, you fall back asleep within 20 minutes.

4. You’re asleep for at least 85 percent of the time you spend in bed.

Importantly, these only apply to long-haul, overnight sleep — “there was less or no consensus,” the authors noted, about “nap-related variables as elements of good sleep quality.” In the absence of more official recommendations, though, we’ve got your guide to better napping right here.

What a Good Night’s Sleep Looks Like, by the Numbers