Sun Exposure Our bigger source of vitamin D is the sun, that is why it is recommended to be exposed to the sun every day for at least 15 minutes without use solar protection. But you need to take precautions. The ideal times to sunbathe are before 10 am and after 4 pm, that is when the sun radiation are not so strong, and it is healthier for your body. within this times, find a shadow spot and use solar protection every two hours, and every time you get out of the water, even if the product is water proof they always end up getting off you skin.