From Water Lilies to Moonflowers In 1751, Swedish botanist Carolus Linnaeus came up with the novel idea of using flowers as clocks. Morning glories open their trumpetlike petals around 10 a.m., water lilies at 11 and so on through evening primroses and moonflowers. A full array of these blossoms, planted in a circle, could indicate the time. It was a whimsical notion. But some 360 years later, scientists are seriously interested in the timekeeping mechanisms of nature. “They’re so ubiquitous, they’re almost a signature of life,” says molecular neuroscientist Russell Foster of Imperial College in London. From cockroaches to humans, Foster explores these internal clocks in a fascinating new book, “Rhythms of Life,” coauthored with British science writer Leon Kreitzman. The authors show how the daily patterns known as circadian rhythms—from the Latin circa diem (“about a day”)—influence far more than our sleep. Heart attacks are more common in the morning. Women tend to go into labor in the evening. Severe asthma attacks prevail at night. The book traces the century-long quest to unravel circadian mechanisms, with some startling outcomes. Even our response to medicines may depend on when we take them. Nature has devised internal clocks for a simple reason: they aid survival. “The early bird really does get the worm,” says Foster—thanks to a silent wake-up call before the last of the wigglers burrow underground around dawn. A mimosa plant spreads its fernlike leaves during the day to create the maximum surface area for photosynthesis, then folds them up at night to reduce water-vapor loss. It’s not a mere response to light. “They do this even when kept in the dark,” says biologist Eugene Maurakis of the Science Museum of Virginia. In humans, the master clock in the brain orchestrates a series of biological events that unfolds in sequence. In the hours before breakfast, the body ramps up digestive enzymes to be ready for the first meal. Temperature and blood pressure rise in preparation for the day’s demands (which helps explain the morning increase in heart attacks). Cells reproduce at set times. Hormones rise and fall—many of them according to a predetermined schedule. The implications for medicine are profound. By timing treatments to complement daily changes in biochemistry, doctors may boost efficacy and reduce side effects. In one seminal trial, medical oncologist William Hrushesky of the Dorn V.A. Medical Center in Columbia, South Carolina, found that by simply reversing the times when he administered two chemotherapeutic drugs, he could extent survival in women with advance ovarian cancer from 11 percent at five years to 44 percent. In all, says Michael Smolensky, editor of the journal Chronobiology International, more than a dozen ailments can currently benefit from carefully timed treatments. In one recent study, he notes, a simple low-dose aspirin at bedtime reduce the rate of preterm delivery in pregnant women at risk for hypertension from 14 percent to zero. Aspirin in the morning had little effect. Surprise? Not to Foster and Kreitzman As they show, timing is everything.