Research from the Harvard Medical School determined that exposure to UVA light can result in a significant rise in endorphin levels. Endorphins are natural opiates produced in the brain that are characterized by a feeling of well-being and a rush of energy. The pineal gland, located in the center of the brain, coordinates most of our life-sustaining functions based on the light information it receives. These light cues affect growth and development, body temperature, blood cell count, fertility and the immune system.
Daily exposure to light also resets the circadian system, and the body’s internal clock. This system is responsible for moods, appetite, energy levels, behavior, sexual desire, and productivity. This would also explain why doses of sunlight can lessen the effects of “jet lag!”