Chasing the Sun summary

The ancient Romans and Greeks were convinced that the sun had healing powers. Hippocrates, often regarded as the father of medicine, prescribed moderate amounts of time in the sun as a way to keep health in balance. The Romans used sun baths, called solaria, as a treatment for ailments such as epilepsy, anaemia, asthma, jaundice, and obesity.

For a long time the practice of sun therapy, or heliotherapy, remained a curiosity of the past. That is, until the turn of the twentieth century, when researchers discovered that sun and ultraviolet light could be an effective treatment for tuberculosis of the skin.

For much of human history, there wasn’t much concern about not getting enough sun. If you lived in certain parts of the world, like the deserts of Africa or North America, the more pressing concern was more likely getting too much sun.

These days, many of us spend our days indoors under artificial lights, working at a desk and staring at a computer screen. Then, during evening and nighttime hours, there are more lights and brightly-glowing screens. As a result, your circadian rhythms are constantly struggling to keep in sync with the actual time of day.

According to the International Agency for Research in Cancer, circadian disruption is “probably carcinogenic to humans,” meaning there is significant evidence that it could cause cancer.

Indeed, former US Navy submarine captain Seth Burton believes that the constant circadian disruption he experienced during his career contributed to the cancer that he later developed. In addition to having no access to sun, Burton’s crew set their watches to a day that was 18, rather than 24, hours long, meaning that they were eating and sleeping at different times every day.

Seasonal affective disorder is one thing, but chronic depression and bipolar disorder are much more serious issues. Yet there is interesting data that suggests our circadian rhythms can play a role in improving a person’s mental health.

A growing number of doctors and researchers have been treating chronic depression and bipolar disorder with chronotherapy, which essentially aims to strengthen a person’s circadian rhythms.

If you understand the importance of circadian rhythms, you’re probably not a fan of daylight saving time, or DST, which disrupts the sleep routines of people across the world twice a year. The collective grogginess that this produces even has a name: social jet lag.

In the German resort town of Bad Kissingen, business manager Michael Wieden has been leading a campaign to get people more attuned to their own inner clock and less obsessed with the clock on the wall.