While it may not be a well-known fact in the general hair care world, the hair growth cycle has a massive impact on the length of hair and shedding. In some cases hair loss can be explained due to medical issues, poor diet, hereditary problems, or even stress.
However, the hair growth cycle plays a big part in hair growth and hair loss, and in a lot of cases your hair health could be linked to this exact cycle.
What is the hair growth cycle?
The hair growth cycle is the process in which hair grows and eventually sheds from our body. The cycle is divided into three main phases: anagen, catagen, and telogen. The fourth phase, exogen, is the point at which the hair leaves the body.
Each and every hair on your head is in a different phase the cycle, contributing to the continuous shedding and growth of your hair. When one hair leaves the head there is already another ready to take its place.
The phases of the hair growth cycle
1. Anagen Phase (The Growing Phase) - Duration: approximately 2 - 7 years
This is the active growth phase and the very beginning of the life of a strand of hair. At this point the hair follicle is producing new hair cells for hair growth. In general, 85-90% of the hair on your scalp is in this phase at any given time.
The longer the hair remains in the anagen phase, the longer it will grow. Genetics largely determine the duration of this phase, meaning it can be hereditary as to how fast you can grow new hair.
2. Catagen Phase (The Transition Phase) - Duration: approximately 2 - 3 weeks
At this stage the hair strand will stop growing. The categen phase is the shortest of the three main phases, indicating that the hair will essentially become independent of the dermal papilla, where the hair grows from.
This phase serves as a transitional period between growth and rest. Since this phase is so short, it has little impact on the length of the hair.
3. Telogen Phase (The Resting Phase): - Duration: approximately 3 - 4 months
This is the phase where the hair is in "limbo". At this stage the hair does not grow but stays attached to the follicle. This is where the hair strand is prepped to enter the last phase of its life in the exogen or shedding phase.
Approximately 10-15% of your hair is in this phase at any given time. This phase accounts for the daily shedding of 50 to 100 hairs, which is a normal part of the hair renewal process.
What affects hair growth and shedding?
There are many individual factors that can influence hair growth and shedding. They include -
- Genetics: Hereditary factors can play a role in general hair health. This can come from our genetic makeup and if our parents had hair issues of their own.
- Age: This is common in most people once they reach a certain age. As you age, the anagen phase shortens, and more hair follicles enter the telogen phase, leading to thinner hair. This essentially means that there is increased shedding but less likelihood of new hair growing in its place.
- Hormones: During pregnancy in particular, elevated estrogen levels can prolong the anagen phase, leading to thicker hair. Conversely, postpartum hormones can trigger hair shedding.
- Health and Nutrition: A balanced diet can play such an important role in our health, including hair health. If you are lacking in vitamins or specific nutrients it can greatly affect the rate at which new hair follicles can produce.
- Stress: High stress levels can push hair into the telogen phase at a faster rate. If you suffer from regular stress you may notice that you are shedding more hair than usual. Because the telogen phase is being rushed it can make your hair follicels work overtime. Reduced stress can help to ease the phase back into its regular pattern, thus preserving the usual cycle.
