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Robert Sothern, Willard Koukkari

In their book, University researchers Robert Sothern (left) and Willard Koukkari present the rhythms that govern all life.

The times of your life

Two University authors reveal the innate rhythms that govern organisms from gardenias to Gershwin

By Deane Morrison

Jan. 19, 2007

If you're taking a drug to treat high blood pressure or cancer, you want the right type of drug and the right dosage. But if you take it at the wrong time of day, you could cancel out its effects. Much of the credit for that discovery--and, in fact, for the whole field of biological rhythms--goes to University professor Franz Halberg, one of three early pioneers in the subject and a major source for a recent book by two University authors. In "Introducing Biological Rhythms," retired plant biology professor Willard Koukkari and plant biology research associate Robert Sothern reveal the hidden hand of the clock in virtually every aspect of life, from sleeping and waking to when athletes perform best to the flowering of plants. As Halberg showed, the human body keeps a complicated schedule of rhythms, which we ignore at our own risk. "You can credit him with the fact that many prescription medicines are to be taken at certain times of day," says Sothern. Halberg also found that closely monitoring a patient's blood pressure throughout the day for a week or two could pick out ominous patterns predictive of impending heart trouble or stroke. He regards the practice of measuring a patient's blood pressure only one time as about as useful as trying to deduce the plot of a film from a single frame. The internal clocks of organisms can be set to generate cycles of any length. Seven-day cycles turn up frequently; for example, that's how long it takes the human body to reject an organ transplant. But how in the world do certain cicadas know to emerge from the ground to mate every 13 or 17 years, and how can synchronized flowering and seeding of Chinese bamboo happen every 100 to 120 years? Sometimes, nature's timing works with mind-boggling precision. Nor is timing limited to big events like eating, sleeping and mating. Even individual cells obey the rhythm of an internal clock. To drive home the ubiquity of biological rhythms, Koukkari issued a challenge to the students in his classes throughout his long and award-winning career as a teacher. "I told them that if anybody could name one [biological function] that has no rhythm, the student would get an automatic A," he chuckles. "Many tried, but nobody ever found one." Experiments Sothern did years ago illustrate the dramatic effect of timing. Studying rats that had been inoculated with cancer cells, he found that when treated with chemotherapy during their active hours, the rats fared poorly.

"What applies in humans applies in plants and even bacteria," Koukkari says. "The temporal organization of life is as critical as the structural organization."

"But I cured them of tumors by treating them at their resting time, which was during the light part of their day," he says. That's because when normal body cells are resting, they don't absorb the anti-cancer chemicals. But tumor cells, which have lost their sense of rhythm, readily take them up.

Read your own clock

If you want to detect some of your own rhythms, Sothern suggests monitoring your heart rate (counting for a full minute) or body temperature every two hours throughout the day. Also, try rating your vigor on a scale of 1 to 7 all day long. You may see connections between some of the variables.

Examples of rhythms in the book also run to the familiar, such as the phenomenon of jet lag and the role it seems to have played in the outcomes of major league baseball and NFL games. The common thread, says Sothern, is that the human body reaches its peak in late afternoon, when body temperature, energy and muscle strength are highest. To illustrate, the book quotes a 25-year analysis of all Monday Night Football games played between 1970 and 1994, when the games always began at 9 p.m. Eastern time. When West Coast teams played on the East Coast, the 9 p.m. start time was very late in the day for the East Coast teams. But to the West Coast players, it felt like 6 p.m., or late afternoon. Sure enough, the record shows that West Coast teams won more often--on the road, no less--and by larger margins than East Coast teams under those circumstances. Games played on the West Coast went the same way because the perceived times of day were the same. [Note to International Olympic Committee: How about moving the women's marathon from morning to late afternoon, when the men's is run? The times might improve.] Plants got rhythm, too. Bean plants lift their leaves in the morning to catch the sun, then droop them at night. As vines grow, they rotate their tips in a spiral pattern, completing each rotation in the same amount of time according to temperature. Also, say Koukkari and Sothern, timing is an important factor in applying herbicides. Woe to the farmer who spends big bucks to spread herbicide at a time of day when the weeds aren't susceptible. Although environmental factors such as day length and temperature can shift biological rhythms, "clock genes" keep them more or less stable. That science of these genes is still in its infancy, but it appears they guide the continual reprogramming of organisms' activities to conform with the day-night cycle. For Koukkari, much of the wonder of biological rhythms lies in their universality. "What applies in humans applies in plants and even bacteria," he says. "The temporal organization of life is as critical as the structural organization."