I only used it for like the first month as I didn't want to wear my watch to bed every night. My takeaway was that it read a lot of downtime as sleeping that wasn't actually sleeping. I wake up at 4 a.m. or so all the time, for example, and just lay in bed scrolling my phone till 6 a.m. or so. But that time was tracked by the watch as REM/deep sleep, which was just inaccurate. The distance/GPS though is great, and that's my main use for running.