The Book of Hours

How circadian rhythms control our lives

In 1370, Cologne became the first city to install a large clock in its town square. Almost immediately, a mania developed for precise schedules and timetables. Workers had to start work at the same time, and take lunch breaks of exactly one hour. Three centuries later, Paris became the first city to introduce streetlights, overriding people’s previous inclination to go home to bed when darkness fell. Over the centuries time measurement became ever more accurate, creating the coordination and regimentation that paved the way for the Industrial Revolution.

In The Siesta and the Midnight Sun: How Our Bodies Experience Time, Jessa Gamble, a science writer based in Yellowknife, traces the long history of attempts to manipulate our biological clocks for the sake of progress. In Canada, there have never been so many chains of coffee shops serving so many different kinds of java to the sleep-deprived. The switch to coffee in the formerly tea-drinking countries of Asia has followed the rapid spread of industrialization there. More troubling than caffeine addiction is the use of cocaine, amphetamines and other legal and illegal drugs that keep people, including soldiers and long-distance truck drivers, awake.

Gamble writes that the U.S. military routinely counters the circadian rhythm of its fighting men with a medication called Modafinil. Could this be why some of them crack up?

Like Sigmund Freud who argued that our unruly sexual urges must be suppressed to create civilization, but then warned that those urges will return to bite us on the behind, Gamble shows that suppressing the body’s natural rhythms, governed by the seasons and the spinning earth, can in the end extract a terrible price. The disastrous 1984 gas leak in Bhopal, India, which resulted in 3,800 deaths, happened while there was only a skeleton crew on the night shift at the Union Carbide chemical plant. The tragic accident that led to the destruction of the Challenger space shuttle was partly caused by the sleep deprivation of the astronauts.

Sleep deprivation has been linked to obesity and it is well known that shift workers have higher rates of cancer and other serious illness. Jet lag makes one unable to function for several days. Gamble tells us little that is new about such common problems, but I did enjoy her report on using an app on her iPhone for the management of jet lag—the Virgin Atlantic Jet Lag Fighter that instructs her when to eat and when to go to bed before, during and after her flight. Although she had crossed eight time zones between Yellowknife and a TED conference in Oxford, England, she apparently felt fine.

The Siesta and the Midnight Sun is a loose collection of anecdotes and facts about circadian rhythms, which are universal in the animal and human world. Sunlight—its angle, intensity and duration—carries information that our cells can decode even if our conscious mind cannot. We need the short wavelengths (blue light) to wake up. Sunlight tells birds (who can feel it through their head) when to migrate and caribou when to mate so that their young are born at a time when plenty of food is available. In people, the natural rhythms are muted, yet it seems human conception is more likely to take place in early summer and more babies are born in spring than in other times of the year. Suicides are seasonal—surprisingly, they peak in May and June. Crime rises in hot weather.

Memory and alertness increase through the day. The liver’s ability to detoxify peaks at around 6 p.m. Body temperature is lowest at dawn, higher in the evening. The reason it is important to understand circadian rhythms is that such understanding could change the way medicine is practised. Chronotherapy, Gamble writes, is a word we will be seeing a lot in the future. It means synchronizing medical treatments with circadian changes in the body.

Jessa Gamble has a gift for communicating her excitement about nature and the perfection of its design. She clearly loves her subject. But I wish she had written a more rigorous book. The Siesta and the Midnight Sun is too casual and chatty, with no endnotes or bibliography. She refers, for instance, to the link between sleep disturbance and schizophrenia, one of several topics about which I would have read more had she provided a source. She interviews many of her friends but not the leading scientists in the field of circadian clocks—Jeffrey Hall, Michael Rosbash and Michael Young, who have just won the Canada Gairdner International Award for identifying a small group of genes that governs periodicity in organisms. It is a major omission.

Her best stories are about the Far North. She describes the Arctic night lasting 100 dark days and the summer sun that never sets, inducing weeks of euphoria, constant partying, manic energy. The Inuit, she observes, regain their traditional culture during the active summer months but cannot follow the traditional winter lifestyle since they are now on the white man’s schedule. The traditional winter would involve just being with their families, eating the meat set aside from the summer hunt and sleeping a lot.

The Canadian North is a natural laboratory for the study of body clocks and one wonders why no research institute has been set up there for that purpose. It is possible that the intractable problems of teen suicide and poor school performance in northern communities could be alleviated by, say, putting full-spectrum lights (a treatment for depression) into schools. It is certainly worth a try.