Anything that was sooo frightening that you need to leave a light on in your roo!

Anything that was sooo frightening that you need to leave a light on in your room or house at night?

I have heard of some people(even me, at times too! ) that because of either nightmares or things on t.v. or movies or whatever has happened to them in general..they HAVE to have that light on, no matter what...even if it upsets somebody who is trying to sleep right near them!! OR they have to have the radio on, or just something to calm them down, so that they can sleep at night!
Also some collect nightlights as well! Or use flashlights, or knives or guns near their beds. or under their beds...so what about you?
and why?

thanks!

Pretty much the only time I sleep with the light on is when I fall asleep reading a book. The body makes serotonin when you are asleep. Light tells the brain it is daytime, so the brain does not allow serotonin production. So I like to keep it dark and cool. Grew up on a farm and it was quiet (except for the critters, now and then) and dark. Moonlight is nice, so is a good starry night.