A recent study from the U.S National Library of Medicine reveals 91 percent of people who work indoors have below average vitamin D levels.

Known as the "sunshine vitamin," doctors say vitamin D is essential for maintaining good health.

"We know we need a good amount of vitamin D to make normal bones, that's undisputed. There is some research that says we need vitamin D levels to be normal in order to have normal blood pressures, nromal immune function, normal mental health as well as normal skin health," says Dr. Roberta Weintraub.

Your doctor can find out your vitamin D level with a simple blood test.