This hormone - the sunlight - is widely available. It stimulates and soothes. It is a source of vitamin D which is essential for bone production and proper functioning of the immune system and it generally acts as a universal antiseptic. It stimulates serotonin production which is an anti-depressant. However, the excess of sunlight may cause many health problems and diseases, including allergies, skin burns, skin cancer, stroke, and excessive dilation of blood vessels. The author discusses properties of the sunlight, its effect on human body and proper way of sunbathing.