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.

When it comes to the reason why we have nightmares, we're still debating that. It's a new area of research, nightmares. And the way I like to think about it is, our brain - we have stress during the day and our brain needs to learn to process this stress.

So we go through in the beginning of the night, we go into the really deep stages of sleep and we actually cycle through. So, when you go down to the deep stage, then you go back up and you actually come into something called REM sleep, which is after about 90 minutes.

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.

So someone who is a child usually goes to bed about 8:00 or 9:00 at night, but then when they have a circadian rhythm shift, it shifts later. And this is natural. And they start to go to bed at 11:00, 12:00, 1:00 and they want to sleep later. So we see this a lot in teens.

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

So you have Sleep Stage One, Two, and then Three/Four. One is a little bit lighter stage of the quiet, non-REM sleep and then Three/Four is really deep, deep sleep. And what you want is, you actually want a number of - you want to go through all of these stages throughout the night.