Here are some comments from Dr. Guy Schenker, concerning sunlight. Receiving adequate sunlight is as important as taking any nutritional supplementation. The doctor's offices, here in the United States, tend to start getting more crowded in October or November with colds, flu and other ailments that come about from lack of proper nutrition and if the truth be know caused from lack of sufficient sunlight on top of lack of vitamins and minerals.
Chances are, inadequate light intake is a part of the problem.
Adequate sunlight can be an important part of increasing your vitality. This condition is strongly correlated with unnatural light entering the eyes as well. You see, when the light hits the optic nerve, it is carried to other parts of the brain in addition to the vision center. Particularly it is carried to the hypothalamus where it is an essential nutrient to regulate hormone balance and autonomic nerve balance. In the late 1800s' early 1900s' sunlight treatment was one of the prominent treatments used to build up health.