For How Long Does My Hair Grow?

The hair cycle consists of many phases. The growing phase (called anagen) is the most relevant time to ascertain hair length. This phase of the hair cycle lasts for about one thousand days (three years). The hair grows at an average speed of a half inch per month (or six inches per year); therefore, the average length an individual hair strand grows is approximately eighteen inches. Some people's growing phases are much longer (more than five years), and some are much shorter (less than two years). This means that some people can grow their hair down to their feet, while others cannot grow it beyond their shoulders.

Why Is There Such a Large Difference between the Amounts of Hair a Person Should Lose Every Day?

Although the average amount of hair on a person's head is approximately 100,000 strands, not everyone has exactly this amount. Moreover, not everyone's hair cycle is three years. For instance, the small percentage of people who can grow their hair down to their feet may have a five- to ten-year hair cycle! Some people only have a two-year cycle, so they are unable to grow their hair beyond their shoulders. This explains that different people can and will have vastly different normal hair fall amounts. Also, remember that forty to one hundred twenty hairs are only an average. Some people will naturally see more than one hundred twenty hairs fall out, while others will see fewer than forty. In addition, if your average is one hundred, you will not lose one hundred hairs every day. Some days you may find very few hairs; other days you may find lots more hair. So don't panic if you see more hairs coming out, as long as you see less on other days.

How does hair grow?

To the question "How does hair grow?" you're probably thinking, "It doesn't!" and believe me, I share your point of view. However, an understanding of how hair is formed and how it grows is crucial to understanding why we lose our hair and how - potentially - we might one day be able to start growing it again.

The first thing to know is that hair, which we've already seen is made from a protein called keratin, grows from a "follicle". A follicle is sometimes described as a pouch or sac and is comprised of various parts - the pear shaped "papilla" at the base, the "hair matrix" which surrounds the papilla and is where cell division takes place (a process which is mainly responsible for creating the hair itself), the "root sheath" and the "hair fiber". A sebaceous gland which produces sebum and tiny muscle fibers called "arrector pili" are attached to the follicle.

So, those are the basic building blocks, how do they work together to produce a growing hair? The crucial thing to realise here is that hair doesn't just grow, it grows in phases, the main phases being anagen, catagen and telogen. Here's a quick rundown of what happens in each of these phases:

Anagen - In this stage the cell division in the follicle mentioned above is taking place rapidly and this causes the hair to grow (about 10cm per year). Hair on the head (and let's face it, that's the area most of us are interested in) remains in this phase for around 2-3 years, occasionally longer - even as much as 6 years. Around 85% of hair is in this phase at any one time.

Catagen - This phase is known as a transitional phase and lasts for around 2 to 3 weeks directly after the anagen phase. The hair follicle shrinks and the lower part is destroyed.

Telogen - The resting phase. The hair does not grow during this period and for head hair this phase lasts about 100 days. 10-15% of hair is in this phase at any one time. When this phase is complete the anagen phase is entered once more and a new hair begins to grow, pushing out the old hair if it has not already been shed. It is normal to lose around 50-100 hairs for this reason each day.

That's it, basically. Simple, isn't it?!