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.
The sun-bath should be pleasant and, if it is taken progressively, will never cause discomfort. Care must be observed in the employment of sunbathing, in cold or damp weather. Only the hardy can enjoy them or profit by them under such circumstances. Those in poor health should avoid them during such weather, although these need them most. If a warm room is available for sunbathing the weakest may continue them.
Medical circles, in writing about sunbathing, frequently stress the Alps and how certain sections of these are especially favored with sunshine. Not only is this largely inaccurate, but there is the more important fact that we cannot all go to the Alps and are forced to make use of the sun where we are.
In most parts of the earth inhabited by man there is sufficient sunshine to meet his needs and the needs of the teeming flora and fauna about him. There are sections in which there is little winter sunshine and from which the sick will do well to retreat when winter comes.
It is cooler in the high mountains, there are more ultra-violet rays and, if one is above the clouds, there are more sunny days, but the fact still remains that there is sufficient sun and favorable conditions for sunbathing in the valley or at the sea-shore.