Hello & welcome @Llis
You can correct the sleep start/end time from the Fitbit app on your phone/tablet.
- From the Today page in the app, tap on the Sleep tile, not the "t" sign to open the Sleep page
- Swipe up until you see the tracked sleep that you want to correct
- Tap on the incorrect tracked sleep to open the sleep metrics
- Tap on the pencil icon in the upper right. This will open the Edit Sleep page.
- Tap on the time that you want to correct - Sleep Start or Sleep End. This will open a mini window.
- You can tap on the hour and minutes and use the clock to enter the correct time. Then tap OK.
Alternatively, you can tap on the keyboard icon in the lower left and use that to correct the time. Then tap Ok - When you've finished correcting your Sleep Start/End time, tap Save in the upper right. This will close the Edit Sleep page and take you back to the Sleep metrics page.
BTW, these steps are for Android. I think the steps for iOS are similar.
Rieko | N California USA MBG PE