I have a Band 2 and its sleep tracking is amazingly informative. It'll tell me how many times I woke up (I never notice), how much quality sleep I got (I never notice)...
...last night for example - I got 7h 41m sleep. 2h 2m was 'restful'. 5h39m was 'light'. I woke up twixe and it took 4m to fall asleep. I burned 627 calories and obtained 97% efficiency. However, I have absolutely no idea how it's of any use whatsoever.
I mean, what exactly can one do about one's sleep, when one is, er, asleep?
I'm grown-up enough to know when I'm tired and need to go to bed; don't drink caffeine late at night; and I wake up to go to work. The stuff inbetween just happens. I don't need a sleep tracker to tell me all that.
I suspect, in some ways hope, I'm just missing something and need educating on how to use the data.