On my Active2 SH sometimes logs more that one sleep record overnight. It sometimes logs a sleep record while I watch TV late at night!. Maybe because I am still and relaxed it assumes I'm asleep. After there is a gap which represents going to bed and then the real sleep record starts.
I used to be able to click on the first sleep log (they have their own start/stop time) of the night and delete it leaving just the correct one. I can't seem to do that anymore. The records still have their own start/stop time but I can only find an option to delete the whole nights logging.