Catching up on lost sleep? Almost impossible

New research shows people who are sleep-deprived may think they're caught up after a 10-hour night of sleep but that is not the case.

We spoke to Dr. Carl Bazil, a neurologist and Director of the Epilepsy and Sleep Division at Columbia University's Comprehensive Epilepsy Center.

" There's a lot of research that shows you can catch up on sleep but it takes a lot longer than most people think." said Dr. Bazil.

" If you are deprived of sleep, say you get six hours sleep a night for several days, you will show deterioration in your attention and in your memory and that accumulates over time. So if it's one night, it's not a big deal, if it's two nights you start to show a difference.

" So what happens after that? Well you try to recover sleep; that's what most of us do and you can do that to some extent, but it probably takes several nights depending on how much sleep you've lost.

" There's a number of things that happen if you don't get enough sleep. The most obvious is usually attention and drowsiness. That happens to just about everyone. What happens during sleep is not just rest, your mind is very active, and sleep is a time when you consolidate many kinds of memories and it's actually a time when you process information you've learned during the day. So that's good, it shows that you need sleep, but the more interesting thing is if you don't get the sleep for the right period of time, you'll never learn that information.

" You've lost your opportunity to learn it so the idea that it's good to stay up all night before an exam for example, is probably not good. You're not going to consolidate that information and as soon as you leave the room, you're not going to learn it as well as if you'd gotten a full night's sleep."

So what you're saying is that if you've had a busy day and you learn a ton of information, you're not going to retain it if you don't get a good night's sleep that night?

" You certainly won't learn it as well as if you got the sleep you need," said Dr. Baliz.

" This is a concept called sleep debt. It actually seems to be true. If you don't get the full night of sleep, and believe it or not for most people that's over 8 hours, even for adults. If you don't get that, what happens is you start to accumulate what we call sleep debt and there's a price to be paid there. You have to make that up and the more debt you have the more impaired you get and also the more time it takes to pay that debt back.

" If you get severely sleep deprived, that is, many nights of missing an hour or two or even one night of no sleep, it's probably going to take you several days to make that up.

"If you miss an entire night's sleep you have at least eight hours of sleep debt so if you sleep ten hours the next day you haven't paid that debt back.

" It's not really hour for hour. The best information we have is it's probably at least half of that. What happens in recovery sleep is your brain gets back what it needs the most, we think that is the deeper stage, what we call non-REM sleep, or slower sleep.

You don't necessarily make up the lighter stages of sleep.

" In many industries, say pilots and truck drivers, there are a lot of regulations. They are not allowed to work long periods of time. I've been on flights, and seen pilots lay down and go to sleep for a period of time.

" Doctors are no longer allowed to work more than 24 hrs in a row. It's better. But even over a 24-hour period you will deteriorate. So you have to balance that against the need to take care of a patient; and maintain patient safety; and maintain continuity of care. It's always a trade off.

" For most people with sleep deprivation they don't really realize that they're not functioning as well. That's been shown in testing as well. They don't think that they're that drowsy. They think their attention's OK. But if you test them they're clearly not as good as when they get a full night's sleep.

" If you are completely sleep deprived for 24 hours, you shouldn't be driving because you're functioning like someone who's legally intoxicated."

Dr. Carl Bazil is a Professor of Clinical Neurology and Director of the Comprehensive Epilepsy Center's Epilepsy and Sleep Division at Columbia University

His offices are at The Neurological Institute on W. 168th St. In Upper Manhattan.