A single hair can give a lot of information about you. The hair on your head grows 2-6 years before falling out. Many tiny blood vessels feed the base of each strand. During that time, your hair shaft absorbs chemicals from any drugs you take. It also contains sweat, your body’s natural oils, and any toxins around you. A hair analysis uses special techniques to look closely at your hair under a microscope. The results can show details about your health and habits.