The Hair Growth Cycle Explained: Anagen, Catagen and Telogen
Finding hair in your brush or the shower drain is not automatically a sign that something is wrong. Every scalp hair moves through a planned cycle of growth, transition and rest, and shedding is simply how one cycle ends so the next can begin. The American Academy of Dermatology says it is normal to shed between 50 and 100 hairs a day, and understanding the cycle makes it much easier to tell routine shedding from something worth asking a dermatologist about.
The three phases of the hair cycle
Each hair follicle on your scalp repeats the same sequence over and over. According to the NIH StatPearls chapter on hair physiology, the cycle is divided into three phases: anagen, catagen and telogen.
Anagen (growth): the active phase, when the follicle builds a new hair. StatPearls notes that the anagen phase as a whole can last for several years.
Catagen (transition): a short phase that can last a few weeks, during which the follicle regresses and loses about one-sixth of its standard diameter.
Telogen (rest): the resting phase before the hair is shed. The same source says telogen can last anywhere from a few weeks for eyelashes to nearly one year for scalp hair.
StatPearls also reports that about 10 to 15 percent of all hairs on the body are in the resting phase at any given time. In other words, a healthy scalp always has some hairs on their way out, which is why a certain amount of shedding every day is expected rather than alarming.
How fast hair grows, and what science has not settled
StatPearls puts typical hair growth at about 0.35 millimeters a day, roughly one centimeter a month or 15 centimeters a year. Because anagen lasts for years, that steady pace is what lets hair reach longer lengths before it enters the resting phase. Two people can grow hair at similar speeds and still see very different maximum lengths, because the length of each person's growth phase is not the same.
It is just as useful to know what is not yet understood. The same chapter states that the exact mechanism that controls passage from one phase into the next is not fully known. That is a good reminder to be skeptical of any claim that a shampoo, oil or routine can reliably speed up or reset the cycle. The sources cited in this article describe the cycle; they do not describe a product that changes it.
How many hairs is normal to lose in a day?
The most commonly quoted figure comes from the American Academy of Dermatology, which says it is normal to shed between 50 and 100 hairs a day. The StatPearls chapter gives a somewhat higher estimate, stating that hair from the scalp is shed at approximately 100 to 200 follicles a day. The two reputable sources do not agree exactly, and neither number is a precise line between healthy and unhealthy.
Context matters more than a daily count. Long or thick hair makes shedding look more dramatic, and a day of washing or detangling can release hairs that had already finished their rest phase days earlier. What deserves attention is a clear change from your own normal, not a single number.
When shedding temporarily increases
Sometimes more hairs than usual shift into the resting phase at once. The AAD calls excessive shedding telogen effluvium, and StatPearls says it usually occurs after some stress and can be acute or chronic. The AAD lists situations that can set it off, including:
Giving birth, or stopping birth-control pills.
Having a high fever, an operation, or recovering from an illness.
Losing 20 pounds or more.
Going through a period of heavy stress, such as caring for a sick loved one, a divorce or losing a job.
The timing can be confusing. Per the AAD, most people notice the extra shedding a few months after the stressful event, and after childbirth it usually peaks about four months later. The AAD describes postpartum shedding as normal and temporary, adding that within six to nine months the hair tends to regain its normal fullness. It also cautions that if the stressor stays with you, shedding can be long-lived. StatPearls additionally lists thyroid conditions and vitamin deficiencies among the situations in which this kind of shedding can occur, which is one reason a professional evaluation is useful.
Gentle habits that respect the cycle you have
No routine can promise to change how your follicles cycle, so a sensible care routine has a modest goal: handle the hair you already have gently, especially when it is wet or tangled. Pulling through knots with a stiff tool, sleeping on rough fabric and wearing very tight styles all add mechanical stress to strands that are already in place.
Detangling: the product page describes the Crown Care Detangling Hair Brush as having flexible bristles designed for comfortable, gentle detangling across 3A to 4C textures.
Nighttime: the Silky Long Satin Bonnet is made from satin, which its product page says is meant to reduce friction while you sleep.
Neither item changes the growth cycle. They are simply tools for treating the hair you have with less friction.
When to see a dermatologist
Shedding that continues well beyond the six to nine month window described above, visible patches, a scalp that is painful, itchy or inflamed, or shedding that comes with other symptoms are all reasons to book an appointment. The AAD notes that a dermatologist can tell you whether you have hair loss or excessive hair shedding, and that some people have both. It also says that the sooner treatment begins, the better the prognosis. If you suspect a medication or treatment is involved, talk with your doctor before changing anything.
Sources
This article is for educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any condition. Talk with a qualified healthcare provider about skin or scalp concerns.
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