Index Sleep Monitor
Garmin Index Sleep Monitor is an armband from 2025, sitting in the mid-range band at an indicative $169.
It reads 11 of the 33 signals this comparison tracks. Nothing at all from body composition. Rarer readings it does take: Body Battery.
By sensor class: 10 at high accuracy and 1 at consumer grade. That grade is my classification of the hardware, not a lab test. Those readings come from an optical heart rate sensor, an optical blood oxygen sensor, a skin temperature sensor and an accelerometer. Blood oxygen is measured through the night, not continuously through the day.
Its 7 days per charge are the 8th longest of the 11 devices of its kind here that publish a figure. Rated 5ATM / 50m. It weighs 30 g. No subscription is required.
Upper-arm band for nights only, June 2025. Works without a Garmin watch, but records no steps, workouts, distance or training load, and does not broadcast heart rate.
Key specs
What it tracks
Heart & vitals
Sleep
Activity
Fitness
Sources
https://www.garmin.com/en-US/p/index-sleep-monitor/https://www.dcrainmaker.com/2025/06/garmin-index-sleep-monitor-in-depth-review.html
Buying for battery life? See every device ranked by battery life
Your wearable's data, read against your own normal
MyBodyAI reads COROS, Garmin, Oura, Polar and Withings by logging in, and Fitbit and Pixel Watch through Google Health. Older Garmin history comes from a data export. It learns how you usually sleep and what your resting heart rate usually is, and every day shows where you stand against yourself: recovery, sleep, load and immune scores, a biological age estimate and early warnings. Optional, and separate from this comparison.
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