Nightlights
Kids should be able to sleep in a dark room. Darkness is a strong cue to the body that it's time for sleep. So, try and keep it as dark as possible.
If your child needs a nightlight and you would like them to have on, choose one that is dim and stays on all night.
Don't get one that projects a picture on the wall or rotates stars on the ceiling. You're not trying to give them something to entertain them, you want them to close their eyes.
You also want to make sure the room conditions are the same all night, so don't get a night light with a motion sensor or one that turns off in the middle of the night. When a child stirs at night and the environment is different, that can cause them to wake up more fully. That's not what we want!