A quiet night thought is when you have a thought or an idea that comes to your mind when it's very late at night and there's no noise or disturbance around. It is like when you are lying in bed trying to sleep and your brain is still trying to work, but everything around you is peaceful and quiet.
Sometimes, a quiet night thought can be really interesting or important or even scary, and it may keep you awake for a while. But it's essential to remember that it's okay to have these thoughts and that they are entirely normal.
So next time when you can't sleep and have a thought in your mind, maybe try to write it down or talk to someone about it the next day. That way, you might be able to understand it better and stop worrying about it at night.