[erohead]

Generally most sleep tracking products use actigraphy (measurements of your movement) to track sleep. Pebble partnered with researchers at Stanford back in the day to produce an algorithm for our operating system, which worked quite well and is now open source!

You can read the code and see how the sleep tracking algorithm works here - https://github.com/coredevices/PebbleOS/blob/main/src%2Ffw%2...