The Biology of Jet Lag Video Transcript

Participants

David Folk Thomas , Daniel Wagner M.D., Rochelle Zak M.D.

Summary

Whether you're traveling for business or pleasure, jet lag often keeps you from making the most of your trip. Just about everyone has a tip to offer on how to avoid jet lag, but what really works? Join our sleep specialists as they talk about the biology of jet lag, and what you can do to get your body back on schedule.

Webcast Transcript

DAVID FOLK THOMAS: Welcome to our webcast. I'm David Folk Thomas.

Whether you're traveling for business or pleasure, jet lag often keeps you from making the most of your trip. You've probably heard all sorts of tips on how to prevent jet lag, but what really works?

Here to talk to us about the biology of jet lag and what you can do to get your body back on schedule, we have two sleep experts. On my left, is Dr. Daniel Wagner. He's the medical director at the Sleep-Wake Disorder Center at the New York Presbyterian Hospital in Manhattan. And next to Dr. Wagner is Dr. Shelley Zak. She's an attending physician at the aforementioned Sleep-Wake Disorder Center at the New York Presbyterian Hospital. Doctors, thanks for joining us today.

Let me start with you, Dr. Wagner, and let's talk about jet lag. Lots of people fly out there-- is jet lag a real problem or is it psychological, and we're all just imagining something?

DANIEL WAGNER, MD: Oh, it's a very real problem. And it's due to the fact that we have an internal clock that tends to get set to the time zone we live in every morning and most people's clocks do a pretty good job of that. But, the clock was not designed to suddenly go across the country or across the ocean on a jet plane. It evolved over millions of years to basically, pretty much stay in the same place from day-to-day. And so it has a limited flexibility as to how it can time our internal functions in concert with the external world. It's the light-dark cycle of the external that does the retiming and synchronizes our internal clock to the outside world.

And so when you suddenly zip over to another time zone and there's a different light-dark cycle, your clock is still set to the home. And because of that it tries to make your body function, to sleep and wake at the times like home. But you're not at that time any more. And it takes about an hour per time zone for your clock to catch up to the new time zone.

Because of that, people very often have trouble sleeping at the new time. Particularly, trouble waking up a lot in the second half of the night. And then they're tired and sleepy in the daytime -- both because of that insomnia, but also because their body clock is still on, let's say, New York time when they're in Hawaii. And when you're supposed to falling asleep -- New York time, let's say it's 11 o'clock -- it's only about 5 o'clock in the afternoon in Hawaii.

DAVID FOLK THOMAS: But at least you're in Hawaii. Dr. Zak, can you elaborate more on the light-dark thing that Dr. Wagner was just mentioning?

SHELLEY ZAK, MD: Oh, absolutely. As Dr. Wagner mentioned, we have a biological clock. And our biological clock is actually set to a little bit more than twenty hours. So how is it that we tend to function in a twenty-four hour world? Well, the time and amount at which you see light in the morning, helps set the biological clock. And this is extremely important, because it's one of the treatments for jet lag. And the whole problem is it's light outside, but you're biological clock says you should be sleeping.

And what we look at when treating jet lag is, again, ways to affect the biological clock. And there are two things that can affect it. Number one is the timing of light, when you first see light. And the other is melatonin. And they work at opposite ends of the spectrum. So having light in the morning does the same for you as melatonin in the evening. So you actually sort of dose them across the day from each other.

DAVID FOLK THOMAS: Melatonin, to elaborate on what melatonin is? Just very briefly.

SHELLEY ZAK, MD: Melatonin is a hormone.