Night terrors are very different from nightmares. A lot of people will think they're the same, but they're really not. Night terrors - you want to look at the time of night when you're having the problem. Night Terrors happen in deep sleep. Nightmares tend to happen in a lighter REM sleep.

So, sleep deprivation, and sometimes an insomnia, which is a little bit of a different form, but just getting a lack of sleep, can lead to a number of different decrements.

And you cycle throughout so that you do about five to six cycles throughout the night. And we spend more time in REM later on in the night than we do earlier on.

We've looked at sleep diaries of patients with insomnia, and they'll say that they don't sleep for one or two days. And the body actually has a natural function, after about the third day to start catching up and you get a little bit more sleep the third night. And that's usually what I tell my patients.

Nightmares are distinctly different from dreams in the way that people feel them and experience them. So a lot of people think that a nightmare is something where something is chasing them and you have to wake up screaming. Yes, that's one of the more common nightmares that we see is the person chasing someone or they're being chased.

When you are more awake at nights, they'll toss and turn, they'll think more, they get frustrated. And when that starts to happen, you really don't sleep even more because you're making your body tense and your mind is getting more and more active.

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.