Edit: specifically asking about wearables, like a Garmin watch that’s only tracking HR (and via that, HRV and breathing rate). Thanks!
In: 11
If you are talking about sleep studies, they attach a bunch of wires to your head and can measure how your brain waves change through the night.
If you are talking about phone/smart watch apps, they measure how much noise or movement you make and take their best guess at what stage of sleep you are in based off of that.
Latest Answers