Every hair on your head is on its own schedule. One follicle may be actively producing hair while the one next to it is resting, and a third is releasing a strand that will end up in your brush. Understanding this cycle explains a lot of things that worry people unnecessarily — daily shedding, hair that “won’t grow past a certain length,” and why eyelashes never reach shoulder length.
This article breaks down the three main phases of the hair growth cycle, what happens in each one, and what can push the cycle out of balance.
Where hair actually grows from
The visible strand — the hair shaft — is made of dead, keratinised cells. It has no nerves and no blood supply, which is why cutting it doesn’t hurt. All the living activity happens below the skin, in the hair follicle.
At the base of the follicle sits the bulb, and inside it a small structure called the dermal papilla, fed by tiny blood vessels. Cells around the papilla divide rapidly, push upward, harden, and become the strand you see. When that cell division slows or stops, the hair stops growing — which is exactly what the cycle describes.
The three phases
Hair follicles move through a repeating cycle of growth, transition and rest. Each follicle cycles independently, which is why humans don’t shed all at once the way many animals do.
| Phase | What it is | Typical duration (scalp) | Share of hairs |
|---|---|---|---|
| Anagen | Active growth | Roughly 2 to 6 years | The large majority |
| Catagen | Transition and shutdown | A few weeks | A very small fraction |
| Telogen | Rest, ending in shedding | Around three months | Roughly one in ten |
Anagen — the growth phase
This is the productive phase. Cells in the bulb divide quickly and the strand lengthens steadily. On the scalp, hair grows at roughly a centimetre a month, though this varies between individuals.
The key insight is that the length of the anagen phase determines the maximum length hair can reach. Scalp hair stays in anagen for years, so it can grow very long. Eyelashes and eyebrows stay in anagen for only a few weeks or months, so they stop at a short length and then fall out. Nothing is wrong when your eyebrows don’t reach your chin — that’s just a shorter anagen phase.
Catagen — the transition phase
Catagen is short and mostly invisible. Cell division stops, the lower portion of the follicle shrinks, and the strand detaches from its blood supply. The hair becomes what’s called a club hair: still anchored in the follicle, but no longer growing or receiving nutrients.
Telogen — the resting phase
During telogen the club hair simply sits in place while the follicle rests. At the end of this phase, the old strand is released — often when you wash or brush your hair — and a new anagen phase begins underneath. Some references separate this release into a fourth phase called exogen, the shedding itself.
This is why finding hair in the shower drain is usually normal. Losing somewhere in the range of 50 to 100 hairs a day is widely considered typical for an adult, though the exact number varies with hair density, length and washing frequency.
Why the cycle matters in practice
Once you understand the cycle, several everyday hair questions answer themselves.
- “My hair won’t grow past my shoulders.” Often a combination of a shorter genetic anagen phase and breakage at the ends, not a failure of growth at the root.
- “I shed more in some months.” Follicles are not perfectly synchronised, but seasonal patterns and life events can shift many follicles into telogen around the same time.
- “Trimming makes hair grow faster.” It doesn’t — growth happens at the follicle. Trimming removes split ends, which reduces breakage and preserves length.
- “Treatments take months to show results.” Because a follicle that has just entered telogen won’t produce visible new growth for weeks regardless of what you apply.
What can disrupt the cycle
Anything that stresses the body can push a larger-than-usual number of follicles out of anagen and into telogen at once. Roughly two to three months later, those hairs shed together and the person notices sudden thinning. Common triggers include:
- Significant physical or emotional stress
- Illness with high fever
- Major hormonal changes, including after childbirth
- Rapid weight loss or restrictive diets
- Nutritional deficiencies, particularly of iron and protein
- Certain medications and medical treatments
Genetic pattern hair loss works differently. Instead of pushing hairs into telogen, it gradually shortens the anagen phase and miniaturises the follicle, so each new strand comes back finer and shorter than the one before it.
Persistent or patchy hair loss is worth discussing with a doctor or dermatologist rather than self-diagnosing, since the underlying cause determines whether anything can or should be done.
Supporting healthy hair
You can’t extend your genetic anagen phase, but you can protect the hair that grows and avoid unnecessary disruption. Adequate protein and overall nutrition support the highly active cells in the bulb. Gentle handling — less aggressive brushing when wet, moderate heat, avoiding constant tight tension on the roots — reduces breakage and mechanical stress on the follicle.
For professionals, the cycle is also a communication tool. Explaining to a client why results take months, or why some shedding after a treatment is expected, sets realistic expectations and builds trust far more effectively than promising fast transformations.
Conclusion
Hair grows in cycles, not continuously. Anagen builds length, catagen shuts the follicle down, and telogen rests before the whole process starts again. Knowing this turns a lot of hair anxiety into ordinary biology.
If you’d like to go deeper into hair structure, scalp analysis and client care, the free hair care and hairstyling courses on Cursa are a practical next step.
