Vitamin D Helps Regulate Healthy Cell Growth And Supports Immunity, Heart Health And Healthy Aging D3 Is A Form Of Vitamin D That Is Usually Obtained Through Diet Or Produced By The Skin From The Sun. Poor Diet And Lack Of Sun Exposure Can Result In Inadequate Intake Of Vitamin D For Optimal Health Vitamin D Has The Nickname The Sunshine Vitamin Because Our Skin Manufactures Vitamin D When Exposed To Sunlight, Vitamin D Is Needed In Almost Every Cell Of The Body In Addition To Helping Build Bones, Vitamin D3 Helps Support Immune Health, Healthy Aging And Heart Health Natrol Is The #1 Drug-Free Sleep Aid Brand And A Leader In Mood & Stress