Health · Article

Why Hair Shedding Increases in Autumn and How Summer UV Exposure Is Involved

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In brief

Hair shedding often rises in autumn mainly because hair follicles damaged by summer sun and sweat stop growing weeks earlier, then fall out once the scalp starts to recover. Japanese dermatologists and a 2026 clinic survey link this to poor scalp sun protection, while some researchers note the seasonal pattern itself is only partly confirmed by science.

Many people notice more hair in their brush or drain around October and November. Dermatologists quoted in Japanese media tie this to damage the scalp received from ultraviolet (UV) rays and sweat during the preceding summer, while some medical commentators abroad caution that the "autumn shedding" pattern is not fully settled in research.

How summer sun exposure leads to autumn shedding

Dr. Eri Furuyama, deputy chief of hair outpatient services at Jiyugaoka Clinic, told Japanese outlet ANN (via Yahoo! News Japan) that the scalp collects sweat, sebum and dirt more easily than facial skin. Hair follicles damaged by intense summer UV rays and perspiration stop growing but the hair itself stays attached for months before it eventually sheds in autumn, Furuyama said.

A similar mechanism is described by Warrenton Dermatology & Skin Therapy Center in the United States, which cites a 2010 study finding that UV radiation, more prevalent in summer, pushes a higher-than-normal share of hair follicles into the resting (telogen) phase around July. Because resting hairs typically shed two to six months later, the follicles that entered rest in mid-summer lose their hair in autumn.

A 2026 survey: scalps go largely unprotected

A nationwide online survey of 300 people aged 20 to 60, conducted August 3–12, 2026 by Medical Corporation Tetsuketsukai (I See Clinic) and published via PR Times on August 24, 2026, found that 62.3% of respondents named the scalp as the body part that received the most UV exposure in summer. Despite this, 78.7% said they did little or no scalp sun protection, and 54.3% said they did nothing after a scalp sunburn.

The same survey found 67.0% of respondents had noticed increased hair loss in autumn, yet 85.3% of that group said they had not been aware of any link to summer UV exposure, according to the release.

Seasonal shedding or pattern hair loss? How to tell the difference

Dr. Takashi Ennyama, director of Natural Skin Clinic, told Yahoo! News Japan that seasonal shedding and androgenetic alopecia (AGA, or pattern hair loss) can look similar but have distinct signs, and the two can also occur at the same time.

Seasonal shedding vs. AGA (pattern hair loss), according to Dr. Ennyama
SignSeasonal sheddingAGA
Hair thicknessStays the sameStrands become thinner and shorter over time ("miniaturization")
PatternGeneral, not localizedM-shaped hairline recession and/or crown thinning
Can overlap?Yes, with AGAYes, with seasonal shedding

Starting treatment early with smaller doses is less burdensome than attempting recovery after significant loss.

— Dr. Takashi Ennyama, Natural Skin Clinic, to Yahoo! News Japan

Is autumn hair loss scientifically proven?

UK-based clinic Hair GP states that while many people report shedding more in autumn, "the scientific evidence supporting this claim is surprisingly limited," with some studies showing a slight seasonal increase and others finding no significant correlation. The site attributes much of what people notice instead to concrete, identifiable causes: cumulative summer UV and chlorine/saltwater damage to the hair shaft, and telogen effluvium, a condition in which stress or other triggers push an unusually large number of follicles into the resting phase at once.

Reducing UV-related scalp damage

Based on the recommendations described by Furuyama and by the I See Clinic survey, scalp care during and after summer centres on limiting UV exposure and keeping the scalp clean without irritating it.

Warrenton Dermatology notes that telogen effluvium is usually temporary: affected follicles typically return to producing hair within about six months once the triggering cause resolves. Hair GP's patient guidance advises consulting a doctor if shedding is excessive, sudden, does not improve with basic care, or comes with other symptoms, since underlying conditions need separate evaluation.

Questions

Is it normal to lose more hair in autumn?
Many people report noticing more shedding in autumn, and Japanese dermatologists link this to damage the scalp sustained from summer UV exposure months earlier. However, a UK clinic notes the overall scientific evidence for a true seasonal pattern is limited and mixed across studies.
What actually causes autumn hair loss?
Dermatologists cited by Japanese media point to summer UV rays and sweat damaging hair follicles and the scalp; the damaged hairs stop growing but remain attached for a couple of months before shedding in autumn. Telogen effluvium, in which many follicles enter the resting phase at once due to a stressor like intense sun exposure, is the mechanism commonly cited.
How can I tell seasonal shedding apart from pattern hair loss (AGA)?
According to dermatologist Takashi Ennyama, in seasonal shedding the hair that falls out keeps its normal thickness, while AGA involves strands becoming progressively thinner and shorter (miniaturization), plus M-shaped hairline recession or crown thinning. The two can occur together.
How can I protect my scalp from summer UV damage?
Sources suggest wearing a hat or using a parasol outdoors, applying a scalp-specific sunscreen spray, and keeping scalp-cleansing routines gentle: pre-brushing hair, rinsing with lukewarm water, and massaging shampoo in with fingertips rather than nails.
When should autumn hair loss be checked by a doctor?
Clinics cited in this piece advise seeking medical evaluation if shedding is excessive, sudden, does not improve with basic care, or is accompanied by other symptoms, since conditions such as AGA or other triggers of telogen effluvium need separate diagnosis.

How the world is telling it

Sources

  1. Yahoo! News Japan — AGAと季節性の抜け毛の違い (Dr. Ennyama, Natural Skin Clinic)
  2. Yahoo! News Japan (ANN/テレビ朝日) — 秋は抜け毛が増加 夏の紫外線が原因か
  3. PR TIMES — 夏に最も紫外線を浴びた部位は「頭皮」が62.3%で1位|秋の抜け毛増加と頭皮ダメージに関する実態調査 (I See Clinic)
  4. Warrenton Dermatology & Skin Therapy Center — Does Hair Loss Get Worse In Autumn?
  5. Hair GP — Debunking the Myth of Seasonal Hair Loss

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