What Makes a Good Night's Sleep? Efficiency, Falling Asleep, and Waking at Night

How long you sleep is only half the picture; how well you sleep in the time you give it is the other. Three measures describe that continuity: how long it takes to fall asleep (sleep onset latency), how long you’re awake during the night (wake after sleep onset), and the share of time in bed spent asleep (sleep efficiency). A National Sleep Foundation (NSF) expert panel agreed that, for adults, falling asleep within about 30 minutes, being awake for 20 minutes or less after first falling asleep, and sleeping 85% or more of the time in bed indicate good sleep quality.

This article is general information, not medical advice.

The Three Measures

• Sleep onset latency (SOL): the time from lights out, or getting into bed to sleep, until you fall asleep.
• Wake after sleep onset (WASO): the total time awake between first falling asleep and finally waking up.
• Sleep efficiency (SE): total sleep time divided by time in bed, as a percentage. Long latency and long waking both lower it.

These definitions come from sleep medicine, where they’re measured in a sleep study; at home, a watch or ring estimates them from movement and heart rate.

What Good Looks Like

In 2017, Ohayon and colleagues reported the NSF panel’s consensus on sleep quality. For adults, the panel agreed that these indicate good sleep quality:

Measure	Good sleep quality
Sleep onset latency	30 minutes or less
Awakenings longer than 5 minutes	1 or fewer a night
Wake after sleep onset	20 minutes or less
Sleep efficiency	85% or more

Taking more than an hour to fall asleep indicated poor sleep quality at every age. The panel reached less agreement on sleep stages and naps as markers of quality.

When Yours Fall Short

Trouble falling asleep or staying asleep on three or more nights a week for at least three months, despite enough time in bed, and with effects during the day, is how chronic insomnia disorder is defined. The AASM’s 2021 guideline (Edinger and colleagues) strongly recommends cognitive behavioural therapy for insomnia (CBT-I) as the first treatment. One of its parts, sleep restriction, works by limiting time in bed to your actual sleep time, which raises efficiency, then extending it as sleep consolidates.

Some habits help most people: a regular wake time, getting out of bed if you can’t sleep and returning when sleepy, and keeping the bedroom for sleep.

Wearable Estimates

Watches and rings tend to overestimate sleep and underestimate wake time, because lying still awake looks like sleep. Your device’s efficiency may read higher than a sleep study’s, so follow its trend; see How Accurate Are the Sleep Stages From Your Watch or Ring?

Following It in Kaizora

Kaizora derives Sleep Efficiency, Sleep Onset Latency, and Wake After Sleep Onset for each sleep, naps included, as the AASM defines them, from the one recording (source and device) with the most of that sleep, so a ratio never mixes two trackers. They’re on the Sleep page alongside Time in Bed and Time Awake in Bed. Sleep efficiency is a component of the Kaizora Sleep Score. Add your own reference ranges at 85% efficiency or 30 minutes’ latency to have nights outside them flagged; see Reference Ranges.

The Short Version

• Sleep onset latency, wake after sleep onset, and sleep efficiency describe how continuous your sleep is.
• An NSF panel agreed on 30 minutes or less to fall asleep, 20 minutes or less awake, and 85% efficiency or more as good.
• Regularly falling short, with daytime effects, may be insomnia; CBT-I is the first treatment.

Sources

• Ohayon M et al., “National Sleep Foundation’s sleep quality recommendations: first report,” Sleep Health 3, no. 1 (2017): 6–19. doi:10.1016/j.sleh.2016.11.006
• Edinger JD et al., “Behavioral and psychological treatments for chronic insomnia disorder in adults: an American Academy of Sleep Medicine clinical practice guideline,” Journal of Clinical Sleep Medicine 17, no. 2 (2021): 255–262. doi:10.5664/jcsm.8986
• National Sleep Foundation and Consumer Technology Association, ANSI/CTA/NSF-2110, Recommendations and Best Practices of Sleep Quality.