My uncle keeps the lights all bright, to the highest intensity the light whenever they are all asleep with their baby. He doesn't want to turn it off, or to dim it, to any way darken it. He's scared something will happen to his baby (which I think because he got pretty paranoid watching horror films). My mom on the other hand, turns the light to the minimum intensity while I was a baby and sleeping. She said that I sleep more sound with that setting and that I feel irritated when it's too bright. So you some moms and dads here, do you turn the lights off when your baby is asleep? How does you baby react?
Actually leaving lights on when a baby is asleep isn't that bad because you'll be able to see your kid all the time. If it gives you peace of mind . . . One of my nieces when she was a baby would scream like crazy if the lights were off when she woke up so the parents had to leave the lights on till morning because the kid felt safer when the lights were on.
I have trained my baby girl since she was born that when we go to sleep at night, the light will be turned off in the room but the light from the living room or toilet will not be so it won't be too dark all over the house. Nowadays, she knows very well that when we turn the light off in the room then it is a time for her to settle at night and sleep until morning. She is not scared or afraid at all even though she is still awake in the dark.