The skin produces vitamin D through exposure to sunlight. Lack of vitamin D can result in a form of bone disease, The body needs a minimum of 20 minutes of sun a week to make enough vitamin D to stay healthy. The body cannot obtain enough Vitamin D from the food we eat so it needs to create it from sunlight exposure. A shortage of Vitamin D can cause problems such a rickets. So, except in special cases, some sun is good for most people. Over exposure can lead to bad sun burns and, in the worst case, melanomas (skin cancer). Overall, too much time in the sun is bad because you get first degree burn
Sunlight also helps in preventing and treating depression. People in cloudier climates have higher rates of depression than those in sunnier environments. We should at least spend 20 minutes in the sun in the early morning, at least 3 times a day to absorb enough adequate necessary amount of ultraviolet rays producing vitamin D. Dr. Raymond Johnson of the Tulane School of Medicine exposed people to ultraviolet light. In 90 percent of the test subjects, their cardiac output increased an average of 39 percent. In other words, their hearts became stronger and pumped more blood.