Sunlight boosts your immune system's defenses

Just 10 to 30 minutes of sunlight helps your skin create vitamin D, a vital nutrient that strengthens your immune system. This vitamin D helps regulate key white blood cells, like T cells and macrophages, which are essential for fighting off viruses and bacteria. Research shows adequate vitamin D can lower your risk of respiratory infections, including colds and flu. A 2017 review of over 25 trials found vitamin D supplementation reduced acute respiratory infections by about 12 percent, with even greater benefits for those deficient. This is especially important in winter, when up to 40 percent of people in northern regions lack enough vitamin D. So, a little sun can go a long way for your health.