Kan-mō-ki
Every autumn, a slightly higher percentage of your hair enters the same phase at once, and you notice it in the shower, on the brush, on the pillow. There's a real mechanism behind this, and it has a name in at least one language, which is more than English can say for it.
The mechanism, plainly
Hair grows in three distinct phases. Anagen is active growth, lasting anywhere from two to seven years depending on the hair and the person. Catagen is a short transitional phase, two to three weeks, where growth stops. Telogen is the resting phase that precedes shedding, lasting around three months before the hair actually falls and a new one begins the cycle again underneath it.
At any given moment, roughly 10 to 20 percent of the hair on your head is sitting in telogen. Losing 50 to 100 hairs a day is entirely normal turnover, not loss in any meaningful sense.
What changes in autumn is the proportion. Summer heat and UV exposure tend to accelerate hair into an extended growth phase — more hair, growing faster, for longer. The trade-off arrives roughly two to three months later: a larger cohort of hairs hits the end of that accelerated cycle simultaneously, and moves into telogen together instead of on the usual staggered schedule. The result is a temporary spike, often reaching or exceeding 100 hairs a day, typically for four to six weeks between September and November. The exact biological triggers are still not fully mapped — researchers point to UV damage, the sharp shift in temperature and humidity, and even the resumption of stress and routine after summer as compounding factors, rather than one single clean cause.
A name for it, elsewhere
Japanese has a term that English doesn't bother with: 換毛期, kan-mō-ki. It's the same word used for animals — a dog or a horse shedding a lighter summer coat to grow in a denser one for winter, and the reverse in spring. Applied to human hair, it's less a diagnosis than a description: this is a coat change, not a malfunction.
The distinction shows up in how the two cultures talk about care, too. Western sources tend to frame this as something to manage or treat — an anti-shedding product, a course of action. Japanese sources lean toward a simpler premise: 頭皮も肌の一部です, "the scalp is part of your skin too," meaning it deserves the same daily attention as your face gets, not a special intervention only once symptoms show up. Scalp massage to stimulate circulation is one of the few pieces of advice that shows up consistently on both sides, in every source, regardless of country.
What we'd actually reach for, if asked
Not a treatment plan, since this isn't a condition — more a routine that treats the scalp like skin during the weeks it's doing more work than usual.
Takamichi Hair Kit — shampoo and conditioner, the wash step everything else depends on.
Volo Microfiber Hair Towel — less friction while drying, meaning less mechanical stress on hair that's already turning over more than usual.
Shoji Work Hairbrush — boar bristle, distributes the scalp's own oils down the hair shaft instead of leaving them concentrated at the root.
Najeau Copper Sequence Leave-In Scalp Treatment — copper peptides, applied directly to the scalp rather than the hair itself.
Sunday Scalp Mask — a once-a-week treatment for the part of you that does the actual growing.
UKA Scalp Brush — for the circulation-stimulating massage that appears, almost without exception, in every piece of advice on this season, in every language.
None of this stops kan-mō-ki. It isn't meant to — the hair currently shedding has already made that decision, weeks ago, without asking anyone. What scalp care actually does is quieter and slower: better circulation and a well-maintained follicle environment give the next growth cycle a better foundation, which is a real effect, just not an instant one. It's meant to meet the season with attention instead of alarm, and to make sure whatever grows in next has the best possible start.
Is losing more hair in fall normal?
Yes. It's a well-documented seasonal pattern, not a sign of a problem. A larger share of hair enters its resting phase at once in autumn and sheds together, rather than on the usual staggered schedule.
Why does hair shed more in autumn than other seasons?
Summer heat and UV exposure tend to push hair into an extended growth phase. Two to three months later, that same hair reaches the end of its cycle simultaneously, producing a temporary spike in shedding.
How long does seasonal hair shedding last?
Typically four to six weeks, usually falling somewhere between September and November.
Can scalp care actually reduce fall hair loss?
Not the hair currently shedding — that decision was already made weeks earlier. What scalp care does is give the next growth cycle a better environment to grow in, through improved circulation and a well-maintained follicle.
What does the Japanese term kan-mō-ki mean?
换毛期 (kan-mō-ki) is the term used for animals shedding a summer coat before growing in a winter one. Applied to human hair, it describes the same idea: a seasonal changeover, not a malfunction.