The Beautiful Cure by Daniel M. Davis

Author:Daniel M. Davis
Language: eng
Format: epub, mobi
Publisher: Doubleday Canada
Published: 2018-03-06T05:00:00+00:00

6 Time and Space

The light of day and dark of night bind our lives to time. Because we are moved by the continuous rotation of the earth to face the blazing of the sun and the blackness of space in turn, almost everything about us follows a twenty-four-hour cycle, tuning our lives to the predictable oscillation of our environment. In fact, all life on earth – animals, plants, bacteria and fungi – follows this same rhythm; a rhythm that the rotation of the earth established in living systems probably around 2.5 billion years ago.1

The activities of our genes, proteins, cells and tissues wax and wane not simply up or down according to whether it is day or night, though, but each in its own particular cycle, bringing the human body through all manner of peaks and troughs, wave upon wave. Our deepest sleep is around 2 a.m.; the body is coldest at 4.30 a.m.; at 8.30 a.m. secretion of testosterone is at its highest; our reaction time is fastest at 3.30 p.m.; and at 6.30 p.m. our blood pressure peaks.2 Apparently the best time for sex is 10 p.m.3

The body’s daily rhythm affects our well-being in all kinds of ways. Accidents at work happen more often at night.4 Car crashes peak around 3 a.m.5 Truly catastrophic events, like the Chernobyl nuclear disaster and the Exxon Valdez ship oil spill, also tend to happen at night. Perhaps this is because our alertness dips at night.6 Outcomes of surgery can vary according to the time of day too. Patients are more likely to experience problems if their treatment begins (i.e. anaesthetics given) in the afternoon – although such problems are limited to slight increases in vomiting or pain after an operation rather than anything more serious.7 It is, however, hard to be certain of the underlying causes behind these kinds of observations. The success or otherwise of a surgical intervention, for example, could be affected by the surgeon’s stress or tiredness, the scheduling of more difficult operations at a particular time of day, a change in the patient’s capacity for healing, or the inherent peak and trough in the surgeon’s alertness caused by the circadian rhythm of the human body.

To test if and how the time of day directly affects the immune system, one needs to eliminate these many variables, and to do so many scientists turn to studying animals. There is considerable evidence that the immune response of mice to an infection is dependent on the time of day at which the infection is contracted. Mice are nocturnal. A stronger immune response is triggered in mice given a dose of salmonella bacteria at 10 a.m., early in their rest time, and a lesser immune response is triggered if the animals are infected at 10 p.m., just as they are becoming more active.8 In a separate experiment, mice infected with bacteria which cause pneumonia again reacted most strongly when infected in the morning.9 The mouse immune system, or at least its ability

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