Yes. They're the best of the commercial trackers, at least from what I have seen. I've worked in depth on this, and we were only able to subtly improve on Fitbit's published results using more advanced models. The best models have a Kappa (measure of agreement) compared to human polysomnography scorers of around 0.6. Where 0 would be random chance and 0.8 is the agreement between different human scorers.

I agree with this. I've been using a Fitbit for 4 years, and I can see the difference in my sleep on a good night compared to nights I've had alcohol, worked out too hard, been dehydrated, had too much caffeine late in the day...they all have measurable differences in my sleep.

Do you have a source? Like, I'd pay money for good sleep tracking, (especially if it's fitbit-level money... I would pay more) but everything I've seen thinks that if I'm in bed and quietly, say, reading a book, I'm asleep until I move.

I've been using the Oura ring for that and it works pretty well for me. Unlike the other fitness trackers, its primary focus is sleep. I don't know how well it would handle reading in bed, however.

I'm mostly concerned about reading in bed 'cause I assume if it can't detect that, it can't detect, you know, staring at the ceiling. (though I guess I'm a lot more likely to fidget while staring at the ceiling.) I mean, I could get out of bed to read, but in my experience, that's even worse for sleep than reading in bed.

I work for Fitbit. I don't speak for Fitbit; this is my personal experience. If you get a Fitbit with heart rate tracking, which nearly all have now, it won't rely just on motion. For me it's worked great, showing an awake period at the beginning or end of my time in bed. More on how it works: https://help.fitbit.com/articles/en_US/Help_article/2163#Aut...

If you buy directly from Fitbit's website, the satisfaction guarantee is 45 days so you have plenty of time to try it out and see how well it works for you.

I have a Withings sleep pad that sits under my mattress and I find it significantly more accurate than other decives I've tried.

It also easily tells between activities in bed (even motionless ones like reading or watching) vs sleeping (and all the assorted cycles). It also measures heart rate, breathing (and how many times you stop), and even snoring.

huh. I will look more into the Oura ring. In budget, but not in "buy without research" budget.

My Charge HR with “sensitive” sleep tracking setting was one of my favorite features. It always knew exactly how much sleep I got. I switched to a Garmin 935 and never look at the sleep data because it’s never accurate.