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| We're
born with all our hair follicles already in place. While some
may change in size over time, we don't develop any new ones
after birth.
As
adults, we have about 100,000 individual strands of hair.
It's completely normal to lose some - 40 to 100 strands -
every day. Normal hair loss is the result of the growth cycle
of the follicles, similar to an 'on-off' system. This means
that when an old hair 'dies', the growing phase starts again
for a new hair to replace it. The hair growth cycle has three
different phases:
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The
anagen phase is the growing phase, or the 'on' phase which lasts
for an average of approximately 1,000 days in the human scalp,
but can range from two to six years. During the anagen phase,
hair cells proliferate rapidly. The hair shaft grows in diameter
and the hair reaches maximum length. |
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The
catagen phase lasts only one to two weeks. It is the transitional
or regressive phase, before the resting phase begins. It is
essentially when the hair stops growing. |
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The
telogen is the final resting stage, or 'off' phase. |
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| When
the old hair is in the telogen phase, activity in the hair follicle
is renewed. A new hair in the anagen phase develops and forces
the old telogen hair out. This is when hairs are lost and you
might notice them in the bath or in your brush or comb.
At
any one time, around 90 per cent of most people's hair follicles
are in the 'growing' anagen phase and approximately 10 per
cent are in the 'resting', or telogen phase. Noticeable hair
loss is usually caused by a short anagen phase and a particularly
long telogen phase.
But
in women whose hair is thinning, the follicles have shrunk,
resulting in finer hairs, barely visible to the naked eye.
Eventually the hair follicles shut down completely.
Reference:
Adrogenetic Alopecia. The Growth and Loss of Hair, The Upjohn
Company, 1989.
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| Causes
of Hair Loss |
| There
are lots of reasons why you might start losing more hair...
including pregnancy, a medical disorder, prescribed medication,
poor nutrition, bad hair care techniques or stress caused by
emotional anxiety, surgery or prolonged illness.
But the most common type of
sustained hair loss in women is hereditary hair loss (the
technical name is diffuse alopecia), which accounts for about
95 per cent of cases. It is estimated that 30% of women will
experience hereditary hair loss by the age of 40…a lot
more than you may have realised.
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