Why does putting a pallid on if u can't sleep or return with backbone to sleep minister to?

If i have a nightmare and can't win back to sleep putting the frothy on does the trick.If i spend ages trying to get to sleep and i don't want to obtain up and be more awake putting the light on help me to drift off!Why does putting a pallid on if u can't sleep or return with backbone to sleep minister to?
I presume surrounded by this situation when you put the light on it give your brain something to concentrate on other than the pitch black and your thoughts, which later allows you to drift back sour!
Because, when you were little, mom or dad terrified the 'monsters' away, and they probably turned the light on.
So the street lamp makes you have a feeling comforted.
When my husband traveled and my kids were little, I used to make tracks a different light on every dark - bathroom, bedroom, hall, kitchen..