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.

So when you're in REM sleep, your brain is very active, our body is quiet, but your brain is really processing a lot of things, a lot of emotions; we dream the most in REM sleep. And then you go back down in the deep stages, and so on and so forth.

There's confusional arousals, there are states in deeper sleep that can happen where people will go and they'll disappear and they'll take on some other persona. They'll commit some crime, but it's all when they are in a very deep stage of sleep. So you really need to have a very thorough evaluation.

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.

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.

So the deeper stages of sleep are really those times of quiescence, you're really restoring your body and we have a few different stages of sleep.

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.