Rhythms of Life, by Russell G Foster and Leon Kreitzman

Try as we might, we can't cheat time

The Roman playwright Plautus once condemned the man "Who in this place set up a sundial,/ To cut and hack my days so wretchedly/ Into small pieces." Who wouldn't echo his words in today's hectic 24/7 society?

To make matters worse, our modern electronic time is unnatural. According to Russell Foster and Leon Kreitzman, "There is no longer any connection, so we believe, between our clocks and the rhythmic cycles of nature: the dawn and dusk; the lengthening days and shortening nights reversing as autumn and winter draw in; the waxing and waning of the moon and the rising and falling of the tide." But, as Rhythms of Life shows, we ignore these natural cycles, as well as the body's rhythms, at our peril.

Foster and Kreitzman argue that modern society "is in conflict with our basic biology". Electric lights turn night into day and central heating transforms our homes into oases of summer warmth in bleak midwinter. When we feel sleepy we don't listen to our bodies. Instead we drink another cup of coffee, roll down the car window and "kid ourselves that we can beat a few billion years of evolution."

We can't. Like just about every other living thing, from algae to animals, we have a biological clock, "first set ticking more than three billion years ago", that regulates our circadian rhythms (circa, about; diem, a day). Together they keep our bodies running, "like the conductor of an orchestra". If you upset the body's clock it can seriously damage your health. Shift working is as bad for you as smoking a packet of cigarettes a day.

Body temperature is higher during the day than at night, as are heart rates and blood pressure. For this reason chronobiologists say evening is the best time for athletics: swimmers can cover 100 metres 2.7 seconds faster at 10pm than at 6.30am.

Our cognitive abilities also change. It's no coincidence that many disasters have occurred at night, such as Chernobyl, Three Mile Island and Exxon Valdez. Each of us has a "time signature" that determines whether we're early birds or midnight owls: genes play a key role. Foster and Kreitzman cite research to show that there are "real clock genes influencing real circadian behaviours".

From the search for a "mammalian master clock" to chronotherapy (using biological rhythms to treat diseases), Rhythms of Life will put you in touch with your inner time. Foster and Kreitzman even have an intriguing scientific method for curing jet-lag, which involves resetting the internal clock. Their book is a fascinating mine of information, although the technical detail makes it a dense read. But if, in the 21st century, "we are poised to alter our sense of time" without considering the biological implications, then this is essential reading.

The reviewer's illustrated biography of Einstein is published by Haus