Hair

7 Great Studies to Reflect Upon — Donovan Hair Clinic


Seasonal Hair Shedding: Is there really a Fall Shed?

Humans shed more in the late summer and Fall than they do in the Spring. It’s just a fact. Why that is we just don’t fully know. We have some pretty good theories.

Moulting of hair is common in various animals. Moulting appears to be controlled by a variety of endogenous and exogenous factors. In animals, it seems that changes in air temperature and sunlight exposure have a key role in how animals shed hair.  Overall, sunlight exposure appears to be far more important than actual changes in temperature.

In humans, season shedding was not thought to exist in some of the early medical literature. In 1969, Orentreich offered support for a seasonality of hair shedding when he reported three women in New York who experienced maximum hair fall in the month of November. Orentreich also proposed that a second lesser peak occurred in Spring.

Today, I’d like to share 7 interesting studies which support seasonal shedding phenomenon in both men and women. 

 

Seasonal Shedding: 7 Key Studies to know about

 

Study 1: Randall and Ebling, 1991

Randall and Ebling studied the hair growth parameters every 28 days of 14 healthy males. 

The study was a fascinating one whereby 14 men age 18-39 in Sheffield UK collected beard shavings, shed hair, as well as finger and toe nail clippings every 28 days for 18 months. In addition, every 28 days, hair samples were taken from the study participants from 5 areas of the scalp. The participants were also asked to record the number of hours they had spent outside. 

 Men in the Randall study reported spending more time outdoors in summer than in winter – about 30 hours per week in June and July compared to 11 hours in January and February. 

 The authors found that the proportion of hairs in anagen (by pluck tests) reached a peak in March each year and then fell steadily through September. This findings was true for all areas of the scalp studied including the vertex parietal and occipital areas of the scalp. When the authors examined the bags of hair that were collected from participants, they found that shedding of hair was maximal in August and September and least in March. In fact, the number of hairs lost per day in August was 60 and this was about double the number of hairs loss in March. Interestingly the diameter of growing hairs did not change. 

Beard growth had a different pattern to that of scalp hair. Beard growth was maximum in July and was lowest in January and February. Finger and toe nails did not show seasonal variations in growth. 

 

Study 2: Courtois et al, 1996

 

The Courtois study from L’Oreal Laboratories in France was a fascinating one which involved studying 10 subjects over a period of 8 to 14 years. Four of these patients did not have other forms of hair loss and 6 did. The authors used phototrichograms to document the percentage of hairs in telogen phase as well as standardized hair collection techniques to determine hair shedding rates. 

 What was remarkable in the detailed study was that the percentage of hairs in telogen varied quite significantly in all patients – but particularly among those with other forms of hair loss.

 In 9 of the 10 subjects, there was a link between sunshine hours and percentage of hairs in telogen. The authors found that late summer and early Autumn (August, September and October) were periods of the highest telogen percentages and December January and February were the periods of minimal shedding. The authors identified a smaller peak of shedding in Feb and March. The authors found that the peak hair shedding from hair collections followed the peak telogen rates by 1-2 months. 

 

 Study 3: Pierard-Franchimont and Pierard, 1999

 The authors performed trichograms of 2857 subjects over 2 consecutive years. They found an increased proportion of telogen effluvium between July and October. The lowest rates were found in January. 

 

Study 4: Kunz et al 2008

A 2008 study from Switzlerand by Kunz, Seifert and Trueb examined shedding patterns in 823 women using trichograms. The authors found that telogen rates were lowest at the beginning of February and highest in July. There was a second peak noted by the authors in April  it was less pronounced than in summer. What was remarkable about the Kunz study was just how many women were studied. Certainly, a study of 823 women is quite large. Second, the authors showed that this seasonal shedding occurred regardless of whether or not the patient had female pattern hair loss and regardless of whether or not they were using minoxidil. 

 

Study 5: Liu et al, 2014

Liu and colleagues studied seasonal changes in hair growth patterns in 41  male and female volunteers from China.  Phototrichograms were used to record the percentage of hairs in anagen and telogen. The authors showed that the highest proportion of telogen hairs were in September and lowest in January. In women, these proportions rose form approximately 8 % in January to 12 % in September. 

Study 6: Hsiang et al, 2017

A 2017 study in the British Journal of Dermatology  also supports that people are more concerned about hair loss in the Summer and Fall than in the Winter and Spring. Specifically, a study by Hsiang and colleagues looked at the Google Trends for the search term “hair loss” in Summer, Fall, Winter and Spring.  Compared to the Spring, searches were 5.74 times more frequent in Summer and 5.05 times more frequent in Fall compared to the Spring.  Searches about hair loss in Winter were 2.63 times more frequent in Winter than Spring. Spring was a time of least entries related to hair loss.

 

Study 7: Buontempo M et al. 2023

Similar to the Hsiang et al, 2017 study, authors of this 2023 study evaluated monthly Google Trends data for ‘hair loss’ in the United States from 1 January 2004 to 1 January 2020. The authors’ data showed significant differences in search interest across months; The month with the highest search interest was August, followed closely by September and July. The month with the lowest search interest was the month April followed by February and December.

CONCLUSIONS

The 7 elegant studies to date support that notion that hair shedding increases in late Summer and Fall for humans!

 

 

References

Courtois et al.Periodicity in the growth and shedding of hair. Br J Dermatol, 1996 Jan;134(1):47-54.

Hsiang EY et al. Seasonality of hair loss: a time series analysis of Google Trends data 2004-2016. Br J Dermatol2018; 178(4):978-79   

Liu C et al. Changes in Chinese hair growth along a full year. Int J Cosmet Sci . 2014 Dec;36(6):531-6.

Maurel D et al. Effects of photoperiod, melatonin implants and castration on molting and on plasma thyroxine, testosterone and prolactin levels in the European badger (Meles meles). Comp Biochem Phyiol A Comp Physiol. 1989;93(4):791-7.

Orentreich N. Scalp hair replacement in man. In: Advances in Biology of Skin. Vol IX: Hair Growth. (Montagna W, Dobson RI, eds). Oxford: Pergamon. 1969. 99-108.

Pearson AJ et al. Inhibitory effect of increased photoperiod on wool follicle growth. J Endocrinol 1996 Jan;148(1):157-66.

Piérard-Franchimont C, Peérard GE .L’effluvium télogène actinique: une facette de la chronobiologie humaine.

Int J Cosmet Sci. 1999 Feb;21(1):15-21.

Randall and Ebling. Seasonal changes in human hair growth. Br J Dermatol 1991.

Reinberg A et al. Circadian and circannual rhythms in plasma hormones and other variables in five healthy young males. Acta Endocrinology 1978; 88: 417-27

Smals AGH et al. Circannual cycle in plasma testosterone levesl in man. J Clin Endocrin Metab 1976; 42: 979-82.

Zhang et al. Comparative study on seasonal hair follicle cycling by analysis of the transcriptomes from cashmere and milk goats. Genomics 2019 Feb 16 

Buontempo M et al. Seasonal trends in hair loss: A big data analysis of Google search patterns and their association with seasonal factors. J Eur Acad Dermatol Venereol. 2023 Jul 20.



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