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.

So, more times than not, but not every time, it can be linked to a medical problem, such as menopause, cancer, chronic pain, it can be linked to anxiety and depression. Those are the more common causes.

Some patients are still having insomnia, but it's seems worse to them than actually it is. So, if they say they're sleep deprived, they haven't slept at all in three days; if we actually take them into a lab, most of the time we actually do see they're sleeping on and off here and there.

Really, a nightmare just really has to evoke some sort of, we call it, dysphoric emotion or something uncomfortable. You could be sad, you could be unhappy; you could be scared, anxious. But traditionally, the definition is you have to awaken from this nightmare.

Well, the actual function of the brain, not so sure yet. There's a lot of different theories about it, but when you talk about psychologically in your brain, a lot of people with insomnia, though not all, report that they can't turn their minds off.

There are some that are - REM Behavior Disorder, we'll see some court documented cases. And they really need to have a thorough evaluation with a sleep specialist.

We think is happening in the brain, the way I like to think about it is, it's almost like, you're brain is going through all these stages of sleep and it's developing in children so fast that it's almost like you're shifting gears in a car. And at some point, you actually stall out a little bit, and that's kind of what happens during a night terror.