Me and DH have both got fitbits. DH has only recently got one (because he's convinced he does more steps than me in a day!
he doesn't.)
However, what we've noticed is that the quality of our sleep is so different.
I often get a sleep score of 90. We go to bed at the same time and get up at the same time (generally speaking). His sleep score is around the 50/60 mark.
When we look at the breakdown of sleep, it's remarkable that he gets virtually 0 REM. I yet between 1-2 and a half hours of REM each night. Sometimes his is 20 mins (the most he's had), but usually 0.
No wonder he's so knackered. So, what can you do, if anything, about it? I also wonder how accurate it all is....