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Why do I lose hair?
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 on
the scalp. It's completely normal to lose some - 50 to 100
strands - every day. 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:·
- 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.
- The catagen phase, or the stopping 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.·
- The
telogen is the final resting stage, or 'off' phase.
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.
In the case of common hair loss, male pattern baldness, or
what we call hereditary hair loss, genes and hormones cause
the miniaturisation of the hair follicles, so the hairs become
short and thin so they are 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.
Causes of Hair Loss
There are lots of reasons why you might start
losing more hair than normal: a medical disorder, prescribed
medication, poor nutrition, bad hair care techniques or severe
stress such as emotional anxiety, surgery or prolonged illness.
But the most common type of hair loss is hereditary
hair loss, also known as common hair loss, male pattern baldness
or androgenetic alopecia.
Apart
from heredity, age and testosterone are also believed to be
the cause of hereditary hair loss. It's easy to recognise
as your hair starts to become thinner and lighter on the crown
and the temples. The hair line begins to recede, but the sides
and back stay pretty much the same.
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