If you have any gnomes, they are good at turning the stereo on during the night or ghosts do too. If you do not have either one of those, then do just what jerseygirl said and not have the stereo in the bedroom or make sure it is off. If you have doors to the bedroom though and the stereo is out in the living area, usually it won't wake them up, unless the stereo has been upgraded to speakers in every room.