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'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 a lot of people who work rotating shifts and they work at night, their bodies are set to want to be awake during the day and sleep at night. So there are some people who have a lot of trouble adjusting their rhythms and they have trouble working the night shift, they're sleepy, they're drowsy driving home.

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.

Narcolepsy is a disorder that affects many different areas of life. So in typical patients with narcolepsy, they have something called "excessive daytime sleepiness." So, they're very sleepy during the day. Yet, at night, they're still sleepy, but their sleep is very broken.

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 are some patients who just have insomnia and they've had it since they were a kid and we don't quite know why. So when we look at the cause, we definitely want to treat whatever else is going on, but insomnia often because it becomes its own diagnosis and that requires its own treatment.