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One
in ten scots have red hair
In red hair, nearly all the melanin is present in the form of phaeomelanin.
Coloring red hair is difficult because of this different pigmentation,
and bleaching red hair to a lighter shade is especially hard.
Greying hair
Gray hair is one of the most familiar signs of aging. The age when
greying starts depends on one's genetic inheritance. But in half
of all Caucasoid people, half the hairs on the scalp are grey by
the age of 50.
The loss of hair color is due to a gradual fall in
melanin production in the hair bulb. If you look at the hairs on
a greying head you find a full range of color, from the normal
shade through to white along each hair, and also from one hair to
another. Usually people notice their first gray hairs near their
temples. Then the grayness spreads to the crown, and later to the
back of the head.
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Hair
with no pigment at all
Rapid graying
You have probably heard stories about people who are supposed to
have 'gone white overnight' following some terrible shock or grief.
Treat these tales with caution! A black hair cannot of itself suddenly
turn white. Hairs grow for years with pigment inside them, and since
they are 'dead' there is no process by which the melanin throughout
a hair can be naturally destroyed rapidly (although it may be bleached
by sunlight over many years).
Apparent rapid greying may be due to a selective
shedding of pigmented hair in a person who has some gray hairs which
are retained. Shedding of this kind usually takes several months,
but can happen within a few days. If it does take place quickly
the effects can be dramatic, since the person's grey hairs may not
have been at all obvious until the darker hairs were lost.
Whether stress or shock can cause this kind of
hair loss (known as alopecia areata) is unknown.
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