Overview
White hair is natural and inevitable in the aging process. If you live long enough, your hair color will fade as it hair loses its pigment. Most people begin seeing their first gray or white hairs in their 30s or 40s. Your chances of becoming gray increase by 10 percent to 20 percent each decade after your 30th birthday. Graying is a gradual process, usually requiring many years from the first gray hairs to completely white hair, and some people retain a small degree of hair color even into their senior years.
Hair Color
The average human head contains about 100,000 hair follicles. At the base of each follicle, cells called keratinocytes are responsible for building hair, and melanocyte cells manufacture the melanin that gives our hair its color. Hair melanin begins as eumelanin, which is black or dark brown, or pheomelanin, which is yellow or red. Eumelanin and pheomelanin form numerous combinations to create the variety of human hair colors. Light-haired and dark-haired people alike eventually go gray, but dark-haired people might appear to become gray earlier, since their white hairs are more conspicuous in a head of dark hair.
Graying Process
Scientists have discovered that hair actually “bleaches” itself. According to Science Daily, hair cells manufacture small amount of hydrogen peroxide, but the amount produced increases as you age. This takes away the cells’ ability to produce melanin, leading hair to become progressively bleached of color.
Spectrum of Gray
What people consider gray hair actually is a spectrum of colors, ranging from “salt and pepper” (a mixture of white and dark hair) to gray to silver to icy white. Some people appear gray when their heads display white hair mixed with hair that still is dark. A gray hair results when it has lost most of its melanin, and white coloring indicates that the hair has no pigment at all.
Graying and Stress
You might have heard about people who, after undergoing a shock or an illness, seemingly turned gray “overnight.” Some parents jokingly declare that the stress of raising teenagers has caused their hair to gray. Despite the common belief that stress affects graying, there is no clear link between the two, according to Scientific American. Although stress hormones can encourage the production of free radicals (molecules that damage cells), which somehow disrupt melanin production, many other factors affect how quickly a person becomes gray.
Other Factors
Genetics play a major role in how much or how quickly hair turns white, according to the WebMD website. If your parents began graying at an early age, chances are you will, too. Premature graying also can be a symptom of such medical conditions as thyroid disorders, vitamin B12 deficiency, anemia and certain autoimmune disorders. Smoking might accelerate the process of graying, too.
