Hi, I am Herkko from Finland. When I am watching American movies, I see children when they go to bed that in their sleeping rooms all lights are on,
Is it also in real life or is it only in movies so that we can see the actors better?

In real life, some children, even some adults can not sleep without lights on. Some can sleep better that way. It is not just in American movies, my nieces from Texas, also likes to sleep with some lights on and when they are already sleeping, my brother or my sister-in-law turn off the lights already. Sometimes, it is just an acquired habit.
I also like watching american movies, there are some scenes where parents turned off the lights, then then another scene is showned.
Herkko, just want to share to you, that I am one person who can sleep better with lights on.