Introducing the Hair Growth Cycle
Not every hair is growing at the same moment. In fact, only about 85% of hair follicles are producing new hair at any given time. What are the others doing? Resting. When hairs can grow non-stop for as long as 10 years, that seems fair enough.
This cycle of growth and rest is known as the hair growth cycle. While this cycle typically keeps our hair luscious and full, things can change when the cycle changes. And usually, that cycle changes thanks to something called male pattern baldness (MPB).
Here, we’ve got everything you need to know about the hair growth cycle – and how MPB affects the different stages of hair growth.
The Stages of the Hair Growth Cycle
There are three main phases that your hair follicles go through as part of the hair growth cycle:
- Anagen stage (the growing phase). This is when your follicles are producing hair. At this time, the cells in your skin divide and multiply very quickly, and your hair shaft becomes longer. 85% of your hair follicles are in this phase at any given time. It can last between three and 10 years.
- Catagen stage (the transitional phase). This is when your follicles stop producing hair, as the process of cell division stops. This stage lasts about one to three weeks. Only around 1% of your hair is in this stage. It’s short but crucial because, at this point, the shape of each hair changes. Each hair becomes ‘clubbed’ and disconnects from the follicle, becoming a telogen hair (or club hair).
- Telogen stage (the resting phase). During the telogen phase, your hair follicles rest. That means there’s no new hair growth. However, the hair shaft stays in the follicle for the two to three months of this phase. When the anagen stage starts again, the old hair is pushed out and will shed. About 15% of your hair is in this phase.
Note: Some people refer to a fourth stage, the exogen phase. The idea is that this is the moment when the hair shaft falls out. Technically, this isn’t a separate phase at all, but the consequence of the telogen stage moving back to anagen.
Male Pattern Baldness and the Hair Growth Cycle
Every hair in your scalp normally goes through this hair growth cycle. However, certain genetic conditions – as well as other processes – can affect how the cycle progresses.
Male pattern baldness (MPB) is a genetic condition that affects most men as they get older. It’s a form of hair loss that causes areas of our scalps to stop producing hair. Changes to our hair growth cycle are to blame due to a hormone known as DHT.
DHT or dihydrotestosterone is a male hormone produced naturally by the body. Yet, when it accumulates over time, it’s known to weaken and damage your hair follicles. That process is known as miniaturisation, and, as a result, your follicles stop producing new healthy hair.
The hormone has a particular impact on your hair growth cycle. DHT has been found to shorten the anagen phase (the growth phase) and lengthen the telogen phase (the resting phase). More accurately, DHT causes the catagen stage (the transitional phase) to occur much sooner. That means your hair doesn’t grow for as long while it rests for much longer. As a result, you’ll see more hair shedding, much slower growth, and often areas of baldness spreading across the scalp.
Heads up: If you experience sudden hair loss across your scalp, you may be experiencing telogen effluvium. This is when your hair follicles quickly move from the anagen to the telogen phase due to trauma or stress. The result is that lots of hairs are shed at the same time. Don’t worry, though. It will grow back.
How to Encourage Hair Regrowth
If you’re experiencing male pattern hair loss, you don’t need to just sit back and watch it happen. There are ways you can intervene in the hair growth cycle to encourage hair regrowth.
How? Look for methods that lengthen the anagen phase of the cycle while shortening the telogen phase. Two solutions have been proven to be effective at doing just that:
- Minoxidil: This is a spray that’s applied topically to the scalp and works to increase blood supply to your hair follicles. Minoxidil encourages your resting follicles to enter the anagen phase of the hair growth cycle, where they stay for longer. As a result, hair growth gets a boost across the scalp.
- Finasteride: Similarly, Finasteride encourages follicles to enter the anagen phase of the cycle, while it shortens the telogen phase at the same time. The mechanism here is slightly different. Rather than working topically, Finasteride inhibits the production of the DHT hormone. This way, it prevents the miniaturisation of hair follicles and keeps them healthier for longer.
Minoxidil is effective in about two-thirds of men — Finasteride in over 80%. When used as combined therapy, they have an efficacy of nearly 95%.
Key Takeaways
The hair growth cycle is made up of three main stages: the anagen or growth phase, the catagen or transitional phase, and the telogen or resting phase. These three phases normally keep your hair well-maintained. However, conditions like male pattern baldness can knock it off course.
Minoxidil and Finasteride can help. Both hair loss medications stabilise and boost your hair growth cycle – and for the vast majority, encourage healthy hair regrowth.
FAQs
How long is a full hair growth cycle?
The hair growth cycle is made up of three main stages, and a full cycle can take anywhere from 3.5-10.5 years. The longest portion of the cycle is the anagen, or growth stage, which can take from 3-10 years.
What happens to the hair growth cycle as you get older?
As you age, the anagen (growth) phase of the hair growth cycle shortens, whilst the telogen (resting) phase lengthens. This means that new hair grows for less time, and rests for longer, slowing down the overall hair growth cycle.
How does Male Pattern Baldness affect the hair growth cycle?
Genetic conditions like Male Pattern Baldness mean that the levels of DHT in your body build up, slowing down the hair growth cycle. Hair loss and balding is a normal part of growing older and shouldn’t be cause for embarrassment.
How do I treat hair loss and Male Pattern Baldness?
The best way to treat hair loss and balding is to take a combination of Minoxidil and Finasteride. Used together, these two treatments have an efficacy of about 95% in men.
¹ScienceDirect – Hair Growth – https://www.sciencedirect.com/topics/medicine-and-dentistry/hair-growth
²S.Nikfar, M.Jaberidoost (2014). Hair – https://www.sciencedirect.com/science/article/pii/B9780123864543006102
³Izabela Urysiak-Czubatka, Małgorzata L. Kmieć, and Grażyna Broniarczyk-Dyła (2014). Assessment of the usefulness of dihydrotestosterone in the diagnostics of patients with androgenetic alopecia – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4171668/
⁴DanlanFu, JunfeiHuang, Kaitao Li, Yuxin Chen, Ye He, Yang Sun, Yilong Guo, Lijuan Du, Qian Qu, YongMiao, Zhiqi Hu (2021). Dihydrotestosterone-induced hair regrowth inhibition by activating androgen receptor in C57BL6 mice simulates androgenetic alopecia – https://www.sciencedirect.com/science/article/pii/S0753332221000329
⁵Talel Badri, Trevor A. Nessel, Dinesh Kumar D. (2021). Minoxidil – https://www.ncbi.nlm.nih.gov/books/NBK482378/
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