There is an epidemic of vitamin D deficiency because we don't get enough sun from 10-2:00. UVB rays are not present at other times & they don't go through glass, clothing, sun block, or clouds. We need 10-30 minutes on a large surface area depending on our skin pigmentation and age. There is also a pandemic of osteoporosis, diabetes, hypertension, depression, cancer, heart attacks, strokes, and immune suppression that is the result.