Whenever people talk about the benefits of direct sunlight, those wavelengths make it through clouds (just to a lesser degree). Whereas 5-10 minutes morning exp

Whenever people talk about the benefits of direct sunlight, those wavelengths make it through clouds (just to a lesser degree). Whereas 5-10 minutes morning exposure is plenty without clouds, it is recommended to increase to 15-20 minutes during cloud cover. In both cases, face towards (but don't look directly at) the sun for the best effect.