For most adults, regularly sleeping less than 7 hours is associated with health risks.

My tracker says I slept less than I feel I did — who is right?

Neither is perfect. Trackers can misclassify quiet wakefulness as sleep and vice versa.

Wearables · Health metrics

Sleep duration

How much sleep adults need, why regular short sleep affects health, and how accurately wearables measure total sleep time.

Written by LON6EVITY Editorial Team · Last updated 2026-09-29

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How much sleep adults need

A 2015 joint consensus statement from the American Academy of Sleep Medicine and the Sleep Research Society recommends that adults sleep 7 or more hours per night on a regular basis.

Why it matters

NHLBI explains that ongoing sleep deficiency is linked to a higher risk of heart disease, high blood pressure, diabetes, obesity and depression, and affects attention and mood.

How wearables measure it

Devices infer sleep from movement and heart rate. A 2021 study in Sleep (Chinoy et al.) comparing seven consumer devices with laboratory polysomnography found that many performed reasonably for total sleep time, while performance for sleep stages was more variable.

Limitations

Wearable readings are estimates designed mainly for wellness and fitness. Accuracy varies by device, fit, skin, movement and model. They do not diagnose conditions; discuss concerning or persistent changes with a clinician.

Factors that can affect the result

Schedule regularity
Caffeine and alcohol
Light exposure
Stress
Sleep disorders

Questions people commonly ask

Is 6 hours enough?: For most adults, regularly sleeping less than 7 hours is associated with health risks.
My tracker says I slept less than I feel I did — who is right?: Neither is perfect. Trackers can misclassify quiet wakefulness as sleep and vice versa.

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Sources

Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the AASM and SRS. Watson NF et al., J Clin Sleep Med, 2015.
Sleep Deprivation and Deficiency. National Heart, Lung, and Blood Institute (NIH).
Performance of seven consumer sleep-tracking devices compared with polysomnography. Chinoy ED et al., Sleep, 2021.