Every autumn, the same question pops up: why is there suddenly so much hair in my brush? It’s not your imagination. Research suggests human hair has a mild seasonal rhythm.
Written by Vita Globe Editorial Team | Reviewed against peer-reviewed dermatology research and AAD guidance
Is seasonal hair shedding real?
There’s reasonable evidence for it. A six-year study of 823 women found the share of resting (telogen) hairs peaked in summer and was lowest in late winter[1]. Because resting hairs shed a couple of months later[2], that summer peak lines up with more shedding into fall. Google search interest in hair loss also rises in summer and fall[3].
Caveat: Seasonal shedding is modest and temporary. Heavy shedding, patches, or thinning that lasts for months points to something else[4].
Sources: Kunz 2009 · Natarelli 2023 · Hsiang 2018 · Verified 2026-09-27
In this article
What does the research actually show?
The best-known study looked at healthy women who were concerned about hair loss. Researchers analyzed trichograms (a count of hairs by growth phase) from 823 women over six years. The proportion of resting hairs was highest in summer, with a smaller peak in spring, and lowest in late winter[1].
A different kind of evidence comes from search data. A time-series analysis of Google Trends from 2004 to 2016 found interest in hair loss rose in summer and fall across the eight countries studied[3]. Search data can’t measure hair directly, but it fits with what people report.
Why would shedding peak in fall?
It comes down to timing. A hair that enters the resting phase stays in the follicle for about two to three months before it sheds[2]. If more hairs enter the resting phase in summer[1], you’d expect more of them to fall out in late summer and autumn.
Why hair would follow the seasons at all isn’t fully understood. One idea is that humans keep a faint version of the seasonal shedding seen in many animals, but that’s a hypothesis, not a settled explanation.
How much seasonal shedding is normal?
The AAD says shedding 50 to 100 hairs a day is normal[4]. A seasonal bump may push you toward the higher end for a while. Signs it’s probably seasonal:
- It started in late summer or fall and eases on its own.
- Your part and hairline look the same.
- No clear trigger like illness, surgery, a crash diet or a new medication.
If there was a trigger about three months earlier, it may be telogen effluvium instead[5]. We explain the difference in Stress and Hair Loss: What Telogen Effluvium Is.
Is there anything you can do about it?
Seasonal shedding is a normal cycle, so there’s nothing to “fix.” What you can do is avoid adding extra stress to your hair:
- Go easy on heat styling and tight hairstyles.
- Use conditioner and detangle gently with a wide-tooth comb.
- Eat enough protein and a varied diet so the new growth has what it needs.
- Track it. A monthly photo of your part line tells you more than the hair in your brush.
The honest summary
- Studies suggest a seasonal rhythm, with more resting hairs in summer[1].
- That likely means more shedding in late summer and fall[2].
- It’s temporary and needs no treatment.
- Shedding that lasts, or comes with patches, deserves a doctor’s look[4].
When should you see a doctor?
See a dermatologist if shedding lasts longer than about six months, you notice bald spots or a widening part, or you have other symptoms like fatigue. Long-lasting shedding is evaluated with labs such as thyroid tests, a blood count and iron studies[5]. You can also read about Nutrient Deficiencies That Cause Thinning Hair.
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Frequently asked questions
Why is my hair falling out so much in the fall?
Research suggests more hairs enter the resting phase in summer, and resting hairs shed a couple of months later, which lands in fall[1][2].
How long does seasonal shedding last?
It’s usually a temporary bump. If heavy shedding continues beyond a few months, see a doctor.
Do you lose more hair in summer or winter?
One large study found resting hairs were lowest in late winter and highest in summer[1].
Is it normal to lose 100 hairs a day?
Yes. The AAD says 50 to 100 hairs a day is normal[4].
Do hair vitamins stop seasonal shedding?
No. Seasonal shedding is part of the normal hair cycle. Vitamins help mainly if you have a deficiency.
Sources
- Kunz M, Seifert B, Trüeb RM. Seasonality of hair shedding in healthy women complaining of hair loss. Dermatology. 2009;219(2):105-110. doi:10.1159/000216832
- Natarelli N, Gahoonia N, Sivamani RK. Integrative and Mechanistic Approach to the Hair Growth Cycle and Hair Loss. J Clin Med. 2023;12(3):893. doi:10.3390/jcm12030893
- Hsiang EY, Semenov YR, Aguh C, Kwatra SG. Seasonality of hair loss: a time series analysis of Google Trends data 2004-2016. Br J Dermatol. 2018;178(4):978-979. doi:10.1111/bjd.16075
- American Academy of Dermatology Association. Do you have hair loss or hair shedding? https://www.aad.org/public/diseases/hair-loss/insider/shedding
- Hughes EC, Syed HA, Saleh D. Telogen Effluvium. In: StatPearls. Treasure Island (FL): StatPearls Publishing; updated May 2024. https://www.ncbi.nlm.nih.gov/books/NBK430848/
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH and the FDA. We cite our sources inline and update articles when the evidence changes.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for medical advice. Talk to your healthcare provider before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or caring for a child.
