I hate to be so pessimistic but since Fitbit doesn't measure brain waves (among many other things) any "sleep" data generated by the Fitbit is somewhere between

I hate to be so pessimistic but since Fitbit doesn't measure brain waves (among many other things) any "sleep" data generated by the Fitbit is somewhere between those novelty love tester machines and random bits in accuracy. Don't trust it over your subjective experience.