It's wrong. I don't know if it's the fitbit or the app, but it's very wrong. It says I went to sleep at 10:05 last night, but I was up until at least 12:30 AM, not to mention the time it took me to actually fall asleep. So I know it's off by over 2 hours and 25 minutes. Don't know if I can trust the accuracy of any of the other features.