Week: 535.5 Guest: Dr. Thomas Roth, Ph.D., Henry Ford Health System Sleep Disorders & Research Center, Detroit Topic: Sleep Patterns and Their Purpose- Part One Producer/Host: Steve Girard

NEMA: What happens when we close our eyes and drift away...what kind of patterns exist in our sleep?

ROTH: Basically, what people have to understand...probably the single most important thing to remember about sleep is that sleep is an active process. People sort of think of your brain shutting down when you go to sleep....but what you have to understand is two things: one, sleep is actually two different processes, there's a thing called REM sleep, or rapid eye movement sleep and there's another kind of sleep that's called non-REM sleep. And those are two totally different biological processes and you spend your life, your whole life, in either wake, REM or non-REM. And rather than your brain turning on or turning off, different parts of your brain control your body in each of these three states. So, when you're in REM, your REM brain wakes up, and your non-REM and your sleep brain goes to sleep. When you're awake, your sleep brain goes to sleep and vice-versa. So, really when you go into sleep, you go into non-REM, then you cycle into REM, and then you cycle back and forth for 90 minutes, and then after about eight hours, you wake up.

NEMA: I've heard that they're broken down into specific stages...and do they serve specific purposes?

ROTH: Basically, non-REM sleep can be subdivided...in other words, non-REM sleep is when your brain is reasonably de-activated, globally...although there are parts which are very active, the main thought parts of the brain are de-activated. People break down non-REM sleep into stages one, two, three and four. But those are quantitative differences....as to REM and non-REM, which are totally different states. So, its REM and non-REM are as different from each other as they are from wake. Within non-REM, you have stages one, two, three and four....stage four and three is when you are very, very deeply asleep... it's what children have....if you've ever seen a young child when you can't wake them up, and shake them... that's stage three, four...that's when we're most difficult to wake, and its in the first hour of the night.

NEMA: Is that something we tend to lose as we get older?

ROTH: As we get older, our deep sleep, our stage three, four, seems to disappear...and starting with the age of thirty or forty, it goes down and down and down, til, in our 70's we have zero stage three, four sleep. Still have the same amount of non-REM, but its lighter non-REM sleep. Women lose it slower than men...interestingly enough.

NEMA: So, is that something we're trying to investigate and figure out why older people do, and....

ROTH: Well, we try to understand, one....what does that mean, is that the reason we have increased sleep difficulties as we age? It certainly does seem to be related as our sleep is lighter and more easily awoken as we age. They to figure out why that is....and what the clinical significance of that is, and how to reverse that...but we don't really know that today.

NEMA: We'll continue our discussion with Dr. Thomas Roth on sleep... dreaming...and insomnia, on our next program. I'm Steve Girard.