Sleep tracking has a delicious irony at its center: people now lie awake worrying about their sleep scores. The data can genuinely help — duration honesty, pattern discovery — but only used with the right grip: loose. Here is the owner’s manual for the score.

What Trackers Nail

Duration and consistency — when you actually slept versus the story you tell yourself. The bedtime-drift discovery (you think 10:30, the data says 11:40) is sleep tracking’s single most useful revelation. Trends over weeks: trustworthy.

What Trackers Guess

Sleep stages — the deep-sleep and REM charts are wrist-based inferences, not lab measurements. Directionally interesting, clinically decorative. Do not reorganize your life around Tuesday’s REM percentage; the wrist is estimating.

The Orthosomnia Trap

Clinicians named the phenomenon: sleep-score anxiety that worsens sleep. If a bad score ruins your morning or bedtime becomes a performance review, the tracker is now the problem. The fix: weekly reviews only, or a tracker sabbatical.

The Healthy Usage Pattern

Use scores to test changes (did the earlier caffeine cutoff move the needle over two weeks?), not to grade mornings. And the ultimate override: feeling rested outranks the number. You are the instrument; the wrist is the accessory.

Trust duration and trends, discount the stage theater, review weekly not daily, and let feeling-rested win every dispute. The score works best as a mirror checked occasionally — not a judge attending your bedtime.