When Mary was 35, she noticed an occasional silver strand – which she would promptly pluck out – in her brown hair. As she aged, the number of wiry grays became more noticeable. Now in her 50s, Mary appears to have more gray hairs than brown ones.
Why does hair turn gray?
For some men and women, gray hair begins to develop at an early age. For others, it comes on more slowly. A pigment called melanin gives hair its color. Our bodies begin to produce less melanin as we age, causing our hair to slowly turn gray. As the body stops producing melanin, most people find that their hair eventually turns completely white. Some people, though, have “salt and pepper” hair that never turns completely gray.
One strand of hair can take several years to fully grow. It then enters a rest period for a few months before falling out. This happens throughout life – whether you have gray hair or not. When melanin starts to decrease, the hair follicle produces a strand of hair with less melanin than before. That causes the new strand to grow in gray.
Your hair does not turn gray overnight. In fact, it can take 10 years or longer for all your hair to turn gray. Most people start seeing gray hair between the ages of 35 and 50. Exactly when you will get gray hair depends on your age and genetics. If you want to know when you’ll turn gray, look to your parents for clues.
Premature gray hair
In the classic novel Catcher in the Rye, the central character, 16-year-old Holden Caulfield, notes that he has “millions of gray hairs” on one side of his head. It may sound unusual, but young adults and, rarely, even children can develop gray hair. Early graying most often runs in families and has no other cause. But in some cases premature graying can result from:
- A history of cigarette smoking
- A vitamin-B deficiency
- Certain medications
- Chemicals and toxins
- Chemotherapy treatments
- Exposure to radiation
- Genetic defects
- Hormonal factors
- Poor nutrition
Men tend to turn gray earlier than women, and whites tend to develop gray hair sooner than African Americans or Asians. In African Americans, graying that takes place before the age of 40 is considered premature. Graying before the age of 30 is considered premature in whites.
Stress and gray hair
You may have blamed your children for giving you those silver strands. But contrary to popular belief, there is no scientific evidence that stress – or a good scare – can turn your hair gray.
- Library of Congress. Why does hair turn gray? Accessed: 09/15/2010
- University of Alabama at Birmingham. Gray hair natural part of aging. Accessed: 09/15/2010
- Inomata K, Aoto T, Binh NT, et al. Genotoxic stress abrogates renewal of melanocyte stem cells by triggering their differentiation. Cell. 2009;137(6):1088-1099.
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