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.

Workplace accidents with people who are sleep deprived or people who work shifts and they don't get the right amount of sleep during the day or at night.

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.

Now circadian rhythms become very interesting and problematic for patients because when you become a teenager, your rhythms actually tend to naturally shift.

So people only focus on getting the really deep sleep, but in reality, we spend almost 60% of the night in the stage two sleep.

We actually don't know the function of sleep all that well yet, but sleep is a time of quiescence in the brain.

When it comes to the reason why we have nightmares, we're still debating that. It's a new area of research, nightmares. And the way I like to think about it is, our brain - we have stress during the day and our brain needs to learn to process this stress.