Humans have always sought the rays of the sun to treat a plethora of ailments. The therapeutic use of sunlight is known as heliotherapy. Heliotherapy involves controlled exposure of the skin to sunlight, with graduated increases in exposure time to avoid burning. Due to differences in the types of light rays that are present during the day and during the different seasons, it is recommended that individuals expose their skin to the sun in the morning during the summer and at noon during the winter.1 While many remain skeptical regarding the benefits of sunlight exposure, an evolving science is demonstrating the positive attributes of select wavelengths of light on human health. New technologies are being developed to deliver specific wavelengths of light to treat both physical and psychological ailments. The science behind these photo or light therapies, along with their potential benefits, will be discussed in this chapter.
Heliotherapy and Chromotherapy
To find evidence of the central importance of the sun in human history, one has only to look at the deities that humans have worshipped through the ages. Sun gods can be traced to every continent, and most take a male form. We find sun deities in mythology from Africa, China, Europe, Indonesia, and Japan.2,3,4
In the early cultures, Egypt was perhaps the civilization most influenced by the sun.2,3,4 In Egyptian history, there were at least seven deities associated with the sun, including Ra, and many others followed. The ancient Egyptians recognized the curative powers of the sun and used sunlight to treat skin disorders and wounds. It is thought that early Egyptians constructed temples with rooms specifically designed to radiate particular colors of light. Individuals were placed in these rooms according to their illness. The Egyptians also used gemstones to produce colored light that was focused on sick individuals. This is probably the origin of color therapy, or chromotherapy. The Chinese also have a rich history of using color therapy to treat illness. This practice dates to the second millennium BC.
Like the Egyptians before them, the Greeks used color therapy in the treatment of illness. Sunlight was prescribed for a variety of ailments, including epilepsy, paralysis, asthma, and malnutrition. The Greeks built temples specifically designed to break up sunlight into its component colors of light.1 Each color was used to treat a particular disorder. This practice was named heliotherapy, after Heliopolis, the Greek city of the sun. The term heliotherapy is used to refer to the treatment of human illness with sunlight. Traditionally, heliotherapy involved sunbathing. Sunbathing or sunlight exposure is still prescribed for certain illnesses today, especially seasonal affective disorder (SAD), or as it is commonly known, the winter blues. Most of the time, however, light treatment, or phototherapy, as it is commonly known in the medical field, involves exposure to specific wavelengths ...