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.

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.

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.

If there's a lot of fear that's going on, if there's a lot of anxiety, it's manifesting itself in your nocturnal world so that analyzing it can help open up basically thoughts about what you need to do during the day. So a lot of people who subscribe to the psychoanalysis, the Jungian thought will really focus a lot on dreams, the meaning, and how it can be used to help you during the day.

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.

Sleep paralysis is something that is actually very common. Many people have it, I've had it myself. And what happens is, when you're in that REM stage of sleep, your brain is very active. You're dreaming your most during that stage, you're mind, your eyes are moving, there's a lot going on. It's like fireworks going on in your brain.

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.