The human skin grows hair all over except for the soles of feet and palms of hands. Some hairs are so fine that they are practically invisible.
Keratin is a protein that makes up hair and is produced in the outer layers of the skin in the hair follicles. As the follicles go about producing new hair cells so the old hair cells are pushed out via the skin’s surface. This happens at an approximate rate of six inches each year.
The hair that is visible to you is really a string of keratin cells that have died. On average, an adult head loses around 100 hairs every day but fortunately the average adult head comprises approximately 150 00 hairs. So a couple of strays on your hairbrush isn’t really cause for alarm.
It has been shown at up to 90% of the hair on an average person’s scalp is actively growing at any time. Each follicle has an individual life cycle. The life cycle can be influenced by factors such as disease, stress, age and the types of products used on the hair.
The Lifecycles of Hair Follicles
Hair follicles have three stages to their lifecycle:
Anagen comprises active hair growth. This cycle typically lasts somewhere between two to six years.
Catagen is the transitional hair growth phase which tends to take place over two or three weeks.
Telogen is the resting phase. This stage lasts around two to three months. As the hair follicles reach the end of this phase the hair is shed and replaced by new hair. Thus the growing cycle begins again.
The Causes of Hair Loss
It is not known why some hair follicles grow for shorter periods than others, but there are a few factors that affect hair loss:
- Genes from both parents influence the predilection to baldness
- Abnormal hormone levels play a major role in the cause of hair loss
- Drugs, including those used for treatment of certain illnesses can result in temporary hair loss
- Stress plays a factor in hair loss
- Illness and even childbirth are contributing factors too
- Cosmetic procedures such as dying hair regularly, using bleaches or chemically-strong shampoos can contribute to the thinning of hair. Even styling your hair with curlers or using irons can cause damage leading to hair loss.
Types of Hair Loss
There are a number of different types of hair loss, including:
- Alopecia universalis which causes all of the hair on the entire body to fall out
- Involutional alopecia. This is a natural condition involving the hair thinning gradually as you age. More and more hairs will go into the resting stage and the remaining hairs will become shorter and fewer.
- Trichotillomania is a condition that is frequently suffered by children. This is a psychological disorder involving a person pulling out their own hair.
- Alopecia areata is a sudden onset of hair loss in patches. This usually occurs in children and younger adults and may lead to complete baldness. Fortunately, most people enjoy a return of the hair over time.