Starting from the shortest ultraviolet through the visible spectrum to the longest infrared light all kinds of wavelengths are present in the spectrum of the Sun; varying biological effects may be attributed to each wavelength.
The health-giving quality of light is an ancient experience: as early as in the ancient Egypt the treatment using direct sunlight, heliotherapy was extensively used, and Europe inherited from ancient Greece the knowledge of effects of different wavelengths on the body and health. The real breakthrough in Europe came at the end of the 19th century when sunlight-therapy was used in the treatment of skin tuberculosis. For the success achieved in sunlight-therapy the physician, Niels Ryberg Finsen, was awarded Nobel Prize in 1903. Later on countless scientific studies proved the beneficial effect of various wavelengths on the metabolism, on the nervous and immune systems. Low-intensity polarized light emitted in a broad spectrum has recently brought another breakthrough in healing.
FIGURE 1 – ELECTROMAGNETIC SPECTRUM OF SUNLIGHT AND PENETRATION DEPTH OF VARIOUS WAVELENGTHS IN HUMAN TISSUES