I have a fitbit too, but it doesn't measure my sleep accurately. If my left arm is holding still it thinks I'm asleep even if I'm awake. But If I remember to put it in sleep mode right before I'm about to fall asleep and turn it back to normal mode right after I wake up then it's pretty accurate. Other than that, the fitbit is great! It's helped me lose 32 lbs in the past 5 weeks!