Your athletic performance could be better
Insufficient vitamin D may affect your fitness levels and muscle function. “You may not even realize you’re not performing at your best,” says Paige Waehner, a certified personal trainer and author of The About.com Guide to Getting in Shape. Giamo agrees. “Vitamin D deficiency is linked to increased inflammation. And after intense exercise, the body is inflamed,” she says. “If adequate amounts of vitamin D are already in the bloodstream, then the speed of recovery from intense exercise is increased.” Giamo warns, though, not to take vitamin D supplements if you aren’t deficient in the nutrient because it’s unlikely you’ll improve your athletic performance or recovery rate. “Since vitamin D is a fat-soluble hormone that doesn’t get excreted by the body, it could be potentially harmful if you take too much,” says Giamo.

You can’t get a good night’s sleep
improved the quality of their z’s—they fell asleep faster and slept longer, according to a study published in the journal Nutritional Neuroscience. Of course getting enough shut-eye every night can boost your health, but so can these other vitamin D benefits that could save your life.