So we go through in the beginning of the night, we go into the really deep stages of sleep and we actually cycle through. So, when you go down to the deep stage, then you go back up and you actually come into something called REM sleep, which is after about 90 minutes.

There's a problem for them [teens] when they have to get up and go to school in the morning, they're very sleepy, yet on the weekends, they'll sleep 12 hours, they'll sleep late and then go to bed late and wake up late. And on vacations, it's not a problem.

So you have it, you awaken from it and you can recall, in detail, what just happened, that's a nightmare. So it's very different from a dream where you generally don't wake up from it and you don't have this dysphoric emotion.

There's confusional arousals, there are states in deeper sleep that can happen where people will go and they'll disappear and they'll take on some other persona. They'll commit some crime, but it's all when they are in a very deep stage of sleep. So you really need to have a very thorough evaluation.

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.

So when it comes to circadian rhythms, it's a clock that's basically programmed in our body. So if you think back to times when people lived on farms and we didn't have electricity.

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.