This section is from the book "The Hygienic System: Fasting And Sun Bathing", by Herbert M. Shelton. Also available from Amazon: The Hygienic System Vol III Fasting and Sun Bathing.
Sun bathing is as beneficial and useful during the fast as at other times. The chronic sufferer should have these throughout the course of the fast. Certain precautions are essential. As the fast progresses, the length of the exposure must be reduced, else an excess of sun will depress and weaken the patient. Nervous patients are especially prone to be depressed by over-exposure.
Dr. Gian-Cursio has objected to the sun bath during the fast on the grounds that the anabolic processes are at a standstill during this time. But this is a mistake as shown by the continuance of growth in fasting animals and by the healing of wounds and ulcers during this period. I advise and employ the sun bath in all chronic sufferers while the fast is in progress.
Certain precautions are essential. It is my practice to gradually increase the time of exposure up to the twentieth day of the fast, then gradually decrease it. This rule is not inflexible, for I find it necessary to decrease the time of exposure before the twentieth day in occasional cases, and I find it possible to wait until the thirtieth day before decreasing the time of exposure in some patients.
No patient should be permitted to stay in the sunbath until he is depressed, or feels "washed out," or is left nervous and irritable. Patients suffering from nervous diseases are especially likely to be depressed by a slight over-exposure. In asthmatics, a little too much sun may bring on a paroxysm of asthma. In sufferers from heart disease, a little over-exposure may depress the heart. Over-exposure of patients with tuberculosis of the lungs has been known to induce a hemorrhage. In this connection it should be understood that by over-exposure, I do not mean sufficient exposure to produce a burn. One may overexpose oneself after one has acquired a very deep, dark tan. Sunbathing may be overdone at any time and over sunning is definitely harmful.