I have a Garmin 935 and had a 235 before it and for me the sleep tracking seems to be quite accurate. I can't vouch for the deep/light sleep, but the time of sl

I have a Garmin 935 and had a 235 before it and for me the sleep tracking seems to be quite accurate. I can't vouch for the deep/light sleep, but the time of sleep/wake is almost always correct. The 935 also has "Move IQ" events where it auto-detects certain patterns. It captures when I walk my dog, and even captured some laps I did in the pool the other day. The optical heart rate tracking also looks pretty good.