When you're in the more deeper stages of sleep - REM sleep, your body is quiet, but your mind is actually very active. So it's a time when your body and your brain is restoring itself. It's repairing any cell damage that happened during the day, it's really repairing, like I said, repairing your body, but also helps with digestion, helps with memory.

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.

We actually don't know the function of sleep all that well yet, but sleep is a time of quiescence in the brain.

In general, there are patients with insomnia who - many patients with insomnia will actually over report the lack of sleep that they are getting.

When they [people with insomnia] start worrying about not sleeping, I'll say, "Say the mantra to myself; if I don't sleep tonight, I'll likely sleep tomorrow, and if not tomorrow then definitely the third" because our body has a way of naturally catching up.

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 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.