So when you're in REM sleep, your brain is very active, our body is quiet, but your brain is really processing a lot of things, a lot of emotions; we dream the most in REM sleep. And then you go back down in the deep stages, and so on and so forth.

Really if it's an hour or two after you've fallen asleep because you're in such a deep sleep at that point.

Night terrors are in deep sleep, and they're more common in kids, as are nightmares, but what happens in a night terror is like a flash - we think a flash of some image or something happens in the brain. We don't really quite know what. And it usually ends up with the child screaming almost like screaming bloody murder. It's very scary for the parents or whoever else is around.

There are some people who believe that dreams really are just kind of a throwaway thing. They are just a way of your brain processing what's happening during the day, but there's really no meaning to them; a lot of imagery of just flashes of what happened.

So it's like your brain has a large filing cabinet and it's opening up each drawer and it's taking in various images and memories from the day, consolidating what it needs to and puts in whatever file. And then if there's something that doesn't fit in any of the files and doesn't really belong, you'll forget about it. So it's a way of really getting a succinct way of storing things in your brain.

For some people they say, it's about wish fulfillment, it's about the things you are never able to do in your day you are actually fulfilling at night. There are other people who will say that it's actually telling you something.

There are other people that think that dreams actually do serve a purpose. But what that purpose is, we're not really sure. So some people believe that it actually does have some psychological representation of what's going on in the day, but there's no need to sit and really analyze it.