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.

We have other opposite problems with circadian rhythms that can happen when you - a lot of times with older adults. They start to go to bed at 6:00, 7:00 at night and they wake up at 2:00 in the morning. And they're rhythms actually shift earlier, but sometime it can just kind of miss the mark and shift too much earlier and that's when we need to treat it with bright light.

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's a new line of research showing that people who don't get enough sleep, they're body doesn't metabolize as well. And so they actually - it leads to weight gain. So if you're not getting enough sleep, you might have difficulty losing weight.

People tend to remember their dreams in the morning a little bit better and if earlier in the night, when you're in a lot of deep sleep, if someone wakes you, or the phone rings or something, you're really confused.

So, it's not every patient that I see, but I'd say a good 70% to 80% of the patients when they go to bed it's like a stereo is playing at an 11 or 12 and they can't turn it down, at all. So it makes it very hard for their body to down regulate to be able to go to bed at night.

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