Why do you sleep? Okay we know, it sounds like a pretty dumb question with a fairly obvious answer, but the truth is that scientists have not yet been able to fully figure it out. In fact, it probably should have been on our list of the 25 biggest mysteries of history. Over the last several decades though, using modern technology, researchers have been able to measure brain waves and find out a little bit about what is going on in our heads at night. It’s thanks to these trailblazers that we can bring you 25 crazy facts about sleep.