Off. I hate it when a light comes on, it only means doom to me. My sister can, or could as i don't know her sleeping patterns anymore, sleep through anything whereas the slightest tremor can set me off on high alert. I feel safer with the light off. It means no one is trying to find their way to me XD
I used to sleep with it on, but I usually sleep with it off. Although, for a few nights after that Slenderman hunting thing in the hetalia - axis powers RP...
It depends... Sometimes i fall asleep with my lights on... but i prefer to sleep with the lights off... Only one exception i always sleep with the tv on...