Dreams. Some people receive messages in them. Some people work out their issues in them. Some people are baffled by them. Some people claim they can control them.
Maybe they’re just a way to file away the days events via your subconscious. Maybe they’re portals to worlds unknown. Maybe they’re glimpses into the future, or past. Who really knows?
Where do you go when you sleep? Why do you see what you see?
If you really want to get to know someone, ask them what their first memorable nightmare was. Most of the time it will make you laugh, but to the person who experienced it, it still has the power to horrify.