Those Orcadian Rhythms

The two travelers looked like typical American tourists as they ambled along Rome's Via Veneto. Then an alarm watch jangled on one man's wrist.

"What on earth do I do now?" he asked.

His companion, an Air Force psycholo gist named Sheldon Freud ("a very dis tant cousin of Sigmund -- fifth or sixth"), answered promptly: "Sit down and we'll order coffee." While they sipped their coffee at Doney's, the first man checked the dial on a small instrument hooked to his belt. He was noting his temperature. There was a wire leading from the gauge down his trousers to a rectal thermometer.

"I believe," says Dr. Freud, "that was the first time anyone ever took a rectal temperature while sipping coffee on the Via Veneto."

The unusual activity had a serious scientific purpose. The two "tourists" were working for the Federal Aviation Agency, trying to find out what really happens to jet-age travelers when long flights take them across time zones, expanding or condensing days and nights until mind and body get out of phase with the surroundings.

Adrenal Tides. Such time-zone crossings foul up man's daily physiological cycles, the "circadian rhythms"* that are still one of nature's deepest mysteries. No matter where he lives on earth, man becomes adjusted to daily cycles of activity and sleep that correspond roughly to the cycles of light and dark. But it is by no means a simple matter of day and night. Man seems to have both wakefulness and sleepiness centers, and the two interact--one switching off the other. Man also has temperature cycles; if he stays up late enough, he will feel chilly around 2:30 a.m. And he has daily "tides" of adrenal hormones.

Psychologist George T. Hauty, now at the University of Delaware, designed the FAA project. He was familiar enough with travelers' reports of feeling dreadful for the first few days of a long-awaited European or Hong Kong holiday, but without scientific testing there was no way to know whether the complaints reflected changes in longitude or overindulgence in food and liquor on the plane. What Hauty wanted now was reliable data that might help him predict circadian effects on pilots' performance during long jet flights, on astronauts whose "days" get shortened to less than 100 minutes, and finally, on weary passengers.

Fast Flicker. Backed by the FAA, Dr. Hauty and Dr. Thomas Adams began with four volunteers, all male FAA employees aged 30 to 55, all scientists. For a week they tested the subjects in Oklahoma City to determine base lines for pulse, blood pressure, breathing rate, urinalysis, flicker-fusion time (how fast a light can flicker before it appears to merge into a steady beam), perspiration from the palms (an index of emotional tension), and rectal temperature every two hours round the clock.

Dr. Adams took the first group westward by commercial jet across ten time zones. In Manila the subjects were rushed to a hospital where all the Oklahoma tests were repeated. Marked differences were found, but they diminished after a rest of about four days. They were less marked, and disappeared faster, after the return flight to Oklahoma City.

The next group went to Rome (seven hours' difference). The same tests were performed, and always there was an accompanying psychologist checking reaction times, decision times, concentration and attention capacities--and demanding that the scientists score themselves on a subjective check-off list. A third, 5,000-mile flight southward from Washington, D.C., to Santiago, Chile, which is only an hour off E.S.T., produced negligible changes.

Early on Location. "Shifting rapidly through a number of time zones causes measurable disruptions in both physiological and psychological functions in humans," reports Dr. Freud, coordinator for the project. "It doesn't seem to matter whether people go to the East or to the West. Body functions are thrown out of kilter for three to five days--but apparently less after returning home. Mental adroitness is impaired for about 24 hours."

When the far-flown volunteers were asked to punch a telegraph key on seeing a light flash, their reaction times were almost twice as long as at home. Internal body temperature took at least four days to shift to the new day-night cycle. Heart rate and water loss through perspiration took still longer.

The implications are many, says Dr. Freud. Tourists should relax for a day after a long latitudinal flight. Diplomats and businessmen should arrive at least a day ahead for any big deals. So should soldiers being jet-lifted into combat. The testers are not yet certain whether East-West pilots adjust more quickly after repeated flights, or whether experience teaches them how to compensate, unconsciously for the effects,.of longitude shifts. Still more unanswerable is the question of how well man will adjust to tomorrow's supersonic planes of 2,000 m.p.h. and up.

* From the Latin circa (around) and dies (day), pronounced sir-kuh-dee-an.

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