Currently, it is estimated that over 1 billion people worldwide are vitamin D deficient, largely due to our modern avoidance of the sun. Other scientists have have labeled vitamin D deficiency a pandemic, while more have argued that the number of deficient individuals could actually include up to 50% of the world’s population. For many years, scientific inquiry has focused on the health risks of sun exposure, especially skin cancers, while the risks of inadequate sunlight have gone largely ignored. However, because of the major role vitamin D and light plays in optimizing your health, it’s important to understand how light affects our biology and how you can adjust your lifestyle to safely maximize your light exposure.