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Cheating your body clock

By Jane Brody
NY TIMES NEWS SERVICE
Tuesday, May 29, 2007, Page 16

GRAPHIC: NY TIMES NEWS SERVICE

Anyone who has flown across several time zones for business or pleasure has no doubt experienced jet lag — that days-long feeling that all body functions are out of sync with the new environment. And as soon as you become adjusted, you return home and have to go through it again. It's enough to prompt some people to stay home.

This is especially true for older people, who may finally have the time and money to travel far and wide but find themselves even more bothered by jet lag than when they were young.

Sleep is not the only function affected by jet lag. The digestive tract is off schedule, too. You become hungry at all the wrong times and may have trouble with waste disposal. Less obvious are the disrupted daily shifts in core body temperature and hormone secretions, which are no longer in tune with the day and night in the new environment.

You may arrive at your destination exhausted, feeling mentally and physically out of sorts and performing poorly at things usually done well. That can take the edge off business acumen or leave a traveler guilt-ridden for "wasting" precious, costly vacation time.

Maybe you have tried some of the advertised techniques for countering those disruptive feelings, like the Argonne diet, which involves highly inconvenient and nutritionally questionable fasting and feasting.

Or using melatonin at confusing times for days before and after the trip, or the acupressure technique of the Jet Lag Eliminator, which involves massaging ears and manipulating pressure points every two hours en route.

But no matter what you have done, you still felt terrible for days. Before sacrificing the opportunities to work abroad or fly to far off and exotic places, the traveler should know that there are ways to reduce, although not eliminate, the discomfort caused by quickly crossing many meridians and throwing off the body clock.

Without any effort on your part, many vital bodily functions are regulated by an internal clock called the circadian rhythm — from circa for about and diem for day. The "about" part comes from the fact that in the absence of light these daily rhythms, the body's many clocks, operate on slightly more than a 24-hour cycle.

They are adjusted to a 24-hour rhythm by environmental cues called zeitgebers (German for time-givers), primarily the 24-hour cycle of sunlight and darkness and the rhythmic secretion in the brain of the hormone melatonin, which is released at night during sleep.

The brain's receptors for melatonin are signaled by light that enters through the eyes.

There are zeitgebers of lesser importance, like exercise and general excitement, that have a much weaker effect than the solar day on the body clock. Diet has little or no proven effect, though high-protein foods foster alertness, and a carbohydrate-rich meal with little or no protein may help in falling asleep.

Typically, the most disturbing feature of jet lag is the disruption of the usual sleep-wake cycle. In the March 31 issue of The Lancet, the British medical journal, Professor Jim Waterhouse and colleagues from Liverpool, England, wrote:

"The ease of getting to sleep and staying asleep depends not only on previous wake time, but also on associations with the circadian rhythm of core temperature. Sleep is easiest to initiate when core temperature is falling rapidly or is at its lowest, and most difficult when body temperature is rising rapidly or is high. Waking is the opposite of sleep initiation, because it happens when core temperature is rising or is high."

Normally, in healthy people, core temperature reaches a low point between 3am and 5am, when most people are asleep, and starts rising gradually about 6am, peaking in midday, when most people are fully awake.

There is a second dip in mid-afternoon, the traditional siesta time, prompting those who can to take naps and others to find some caffeine or go for a run to help them get through the day.

The biological disruptions of jet lag are made worse by the fatigue induced by a long flight — the many hours spent in a cramped, dehydrating environment where the air is bone-dry and low on oxygen, the food can be worse than dreadful, and the opportunity for on-board exercise is ever more restricted, in part by security concerns.

TO LESSEN THE TRAUMA

If possible, go a day or two early to give the body time to adjust a little.

These are some important tips for the trip:

— Request an aisle seat when you make your reservation.

— Start out well rested and well hydrated.

— Wear comfortable, nonrestricting clothing.

— En route, drink lots and lots of water.

— Avoid alcohol and caffeine (they are dehydrating).

— Get up to use the lavatory or to ask the flight attendant for water as often as possible, taking the long way around the aisles.

— Try to sleep during the time it is night at your destination. A low-dose sleeping pill or a three-milligram tablet of melatonin, or both, can help.

On arriving in Australia, for instance, day is night and night is day for a New Yorker. But I did not want to spend my vacation days in bed.

I consulted Alfred Lewy, a psychiatrist and an expert on body clock adjustments at Oregon Health Sciences University in Portland. Based on my travel schedule, he e-mailed me a detailed "prescription" for taking, alternately, very low and higher doses of melatonin and taking in and avoiding sunlight depending on the time of day at my origin and destination.

It was so complicated that I gave up the dosing schedule within two days. I resorted to a few time-honored techniques. Melatonin and a sleeping pill helped me get through an uncomfortable night on the plane.

I landed in Sydney in the morning, had a late breakfast with strong coffee (the Liverpool scientists mentioned the drug modafinil as an alternative stimulant) and went for an exploratory walk in the city. Following Lewy's advice, I wore sunglasses until midafternoon, then had a hour or more of unprotected sunlight to help my internal clock learn to stay awake through an Australian day.

An early dinner was followed by an earlier-than-usual bedtime, aided by a 3-milligram dose of melatonin before retiring and a 0.3-milligram dose every time I awoke before 5am, as Lewy had suggested.
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