I picked up a used garmin 945, arrived 4 weeks ago today. I was sick of my old 910 but I also wanted to add sleep tracking since we had a baby coming. She came 4 days later so didn’t get any real pre data i was hoping to get. So far it seems pretty good. For a little while it would end my sleep at 3am or whatever time we got up to feed her and I’d have to manually change it to my actual wake up time. It would then just mark those next couple hours as light no matter if I was awake still taking care of baby or if I was asleep. The last week it seems to be showing me falling back a sleep and has my actual wake up time to the minute, not sure if it learned I wasn’t actually getting up at 3am or not.
Since I need to take it off for work I only trust some of the data like body battery so much, since it will miss a lot of time that would drain it. But when that gets low… man do I feel drained, also it is always low right now.
I had a basic wrist fitbit years ago, came free with a phone or something, that I just used for sleep tracking until it stopped syncing with said phone. The garmin is far more accurate, but we are talking about something tracking movement and heart rate and 6+ years newer.
I find this to be the case with my 945. For the most part just normal activity and sleeping seemed to be about right, or lets call it good enough. But the first TR ride I did with my strap synced to the computer and left the watch on they were off the whole time. Sometimes by over 50bpm. One evening I hit 160+ on my ride and the 945 said my high was like 110 when I was washing my water bottles afterwards. But when I run it seems about right.