Gadgets
How Smart Rings Track Sleep (and How Accurate They Are)
The sensors and algorithms behind ring-based sleep tracking.
· 3 min read
Key takeaways
- Rings use optical heart-rate and motion sensors.
- Finger arteries give a strong signal at night.
- Trends matter more than single nights.
The sensors
Infrared and green LEDs measure blood flow; an accelerometer tracks movement; a thermistor tracks skin temperature.
Sleep stages
Algorithms combine heart rate, HRV and movement to estimate light, deep and REM sleep.
Using the data
Watch weekly trends — late caffeine, alcohol and late meals usually show up clearly.
Frequently asked questions
Products mentioned in this article
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