I guess this makes sense: if your skin makes Vitamin D from sunlight exposure, your body being flooded with Vitamin D at night is going to confuse it—the body m

I guess this makes sense: if your skin makes Vitamin D from sunlight exposure, your body being flooded with Vitamin D at night is going to confuse it—the body must be thinking "Why am I getting so much sun right now? I must not be sleepy." Taking it in the morning is going to be like getting a shot of morning sunshine whether or not you're actually getting sunlight.