Shower before bed or in the morning?? Could make a difference. Vitamin D deficiency is now epidemic proportions, but a strong question is why? I know we are told to wear SPF 90 to walk to the car, but what else contributes? Sunlight through glass may break down Vit D in the skin. But who knew it takes more than 8 hrs to process Vit D formed by sunlight in the skin? So..showering at night may wash away Vit D produced during the day.