In the right hands sunlight is a medicine. Throughout history it has been used to prevent and cure a wide range of diseases, and a few doctors still use its therapeutic properties to good effect. However, at the present time it is widely held amongst certain sections of the medical profession and the population at large that the damaging effects of sunlight on the skin far outweigh any benefits.

Public health campaigns reinforce this message in an attempt to curb the annual increase in skin cancers. Any illusions about tanned skin being a sign of health or providing more than minimal protection to further exposure to the sun’s rays seem to have been dispelled.

Sunlight may cause skin cancer, but there is also evidence that it could prevent a number of very common and often fatal diseases: breast cancer; colon cancer; prostate cancer; ovarian cancer; heart disease; multiple sclerosis; and osteoporosis. When combined, the number of people who die from these conditions is far greater than the number of deaths from skin cancer; which is why the current bias against sunlight needs, in my opinion, to be redressed.

But before going any further, let me explain how I came to write The Healing Sun. Usually books of this kind are written by doctors of medicine, or medical journalists, and not doctors of engineering. However, my background is a little unusual in that for many years, while I was designing or evaluating what could broadly be called solar energy technologies of one form of another — solar collectors; equipment for use in spacecraft; and energy-efficient buildings — I was also studying complementary medicine. Working alongside architects on one particular project I became aware of a ‘lost’ tradition of designing sunlit buildings to prevent disease, rather than to save energy, and I became interested in the healing powers of sunlight.

I began to study the history of sunlight therapy and found that the physicians who practiced this ancient healing art, and the architects and engineers who supported them in their work, used sunlight very differently from the way many of us do today. In comparing this with some of the latest findings from medical research on sunlight and health I have, as you will see, come to some rather controversial conclusions...