Sunlight provides vitamin D but it is not safe for our skin to be exposed from it for the fact that our ozone layer is much depleted and so will not protect us from UV rays. Disclosure to sunlight will indirectly affect the whitening process since it enhances the melanin pigments to the skin, thus, it might delay the whitening process. It's not bad to be exposed to sunlight but at least have protection and be certain, not to be exposed for a long period.