Numerous factors determine both hair loss and hair growth
We are all familiar with hereditary or pattern hair loss in women and men, with perhaps only minimal knowledge of seasonal hair loss or shedding.
I want to share my insight into seasonal hair loss in this blog. A timely communication as those residing in Australia and the Southern hemisphere will be experiencing its peak shortly, being mid to late autumn (May).
In the Northern hemisphere, Europe and the USA, seasonal hair loss or shedding occurs in their autumn (fall) in late October and November.
1 in 20 adults experience seasonal hair loss!
Estimates tell us that up to 5% (1 out of 20) of adults over the age of 25 will experience various extents of seasonal hair loss that results in unusual, more than usual or excessive shedding. That percentage was even higher, particularly in women who have already suffered hair loss.
To a large extent, the growth of hair follicles in animals and humans is mainly regulated by hormones, which are, in turn, influenced by environmental factors like light and temperature via their fluctuations with seasonal changes.
Hair follicles can produce different hair types (length, thickness, texture, curliness, colour) at various times in an individual's life, depending on gene expression and the follicles' capacity to regenerate new hair during the hair cycle.
This ability also allows hair to change to correlate with alterations in season, sexual development, age etc. Melatonin, secreted by the pineal gland, also called the 3rd eye of the body, is how the body interacts with the environment via our other two eyes.
Autumnal hair loss and your hormones
Melatonin is the master hormone affecting many other hormones directly or indirectly, thus varying body functions. For example, one such hormone varies our biological clock during seasonal changes causing hair growth or shedding.
In animals, seasonal changes occur twice a year with coordinated synchronised waves of growth and moulting to produce a denser, thicker, warmer winter coat to provide warmth on winter days and a shorter, thinner summer pelage.
A short winter day (less daylight, i.e. more extended darkness) increases melatonin secretion maximises hair growth in animals and vice versa in summer.
Unlike animals, our hair grows in an inborn, nonsequential rhythm and independently (not synchronised) cyclically.
Seasonal changes in our hair are much more complex and less understood
Since scalp hair usually grows for 3-6 years, it is remarkable that the annual cycle of hair loss is apparent to us at all.
There are very few studies on the variation of annual cycles of human scalp hair and even less on beard and other body hair. Interesting, all the studies concluded with the same findings.
1. Clinical studies have confirmed the existence of annual seasonal hair loss in humans.
2. Regardless of race, both men and women do exhibit one annual shedding in (mid to late) autumn, known as autumnal moult of scalp hair or increased autumnal hair shedding.
3. Some men even experience a 2nd seasonal hair shedding, only a minor one comparatively, in mid to late spring.
4. We have the maximal % of hair in telogen (the non-growing phase) by the end of the summer resulting in increased autumnal hair fall. Conversely, the lowest % in telogen in late winter and early spring.
5. Beard and body hair growth rate was low in winter but increased significantly in summer, even for men with indoor occupations.
6. One French study found summer peaks in semen volume, sperm count, and sperm mobility corresponded with a rise in sex hormones, including testosterone, in men and pubescent boys.
I find this last point most interesting, as an increased level of sex hormone in men reflects a similar pattern seen in animals' summer breeding season.
Because testosterone changes alter hair growth rate, increased testosterone in summer could increase Dihydrotestosterone (DHT) after conversion, which is nearly ten times more powerful as a scalp hair growth inhibitor than testosterone itself.
This might explain the subsequent increased autumnal hair loss.
Paradoxically DHT is a strong growth promoter in body hair like beards, in androgen-sensitive areas in genetically susceptible individuals at pre-determinate times, that might confirm and explain the finding of points 5 and 6 above.
7. Humans retain the ability to respond to changes in day length by altering our melatonin secretion like animals, thus affecting hair growth. Still, it is complicated and compromised by our shift work practice and modern urban environments in which light and dark are artificially manipulated with man-made lighting that probably suppresses our in-born response.
8. Apart from melatonin and sex hormones, other hormones like thyroid hormones also affect hair growth. Optimal levels of thyroid hormones extend the growth phase, stimulating hair cell growth directly (stimulating hair follicles) and indirectly by increasing metabolism (energy supply).
Again, the annual fluctuation of Thyroid hormone levels is affected by seasonal changes that peak during winter and decline to a trough in summer, leading to excessive hair shedding in late autumn.
Please note that people with hypothyroid or hyperthyroid, quite prevalent in human adults, will also experience hair loss.
So why do some people experience autumnal hair shedding?
While most scientists see seasonal hair loss as simply the result of our human evolution and a direct result of nature's seasonal biological clock on our hormones.
Some others explain the phenomenon as being the result of stronger and longer exposure to UV sunlight during summer that generates more harmful free radicals to damage hair follicle stem cells, thus limiting and inhibiting hair growth resulting in degeneration that eventually leads to increased autumnal hair shedding.
In conclusion, the actual mechanism of seasonal hair loss is very complex; it might well be the combination of all the above-mentioned scenarios or other factors that we are yet to discover.
Getting the right hair health advice for hair loss and growth is essential
However, annual/seasonal effects of hair growth loss or shedding have a critical implication for both the public (the consumer) and hair health practitioners:
When you experience excessive hair fall around autumn, don't panic — it could simply be that you are just unlucky enough to be experiencing seasonal hair loss.
Don't stress out because stress is clinically proven to induce hair loss! Instead, consult and seek help from a knowledgeable hair health practitioner or book a consultation at our Activance Clinic.
If you start a hair loss treatment of any form, including Activance, around late summer to early autumn, and you experience more hair falling out weeks later (i.e. in mid-late autumn), do not despair or give up but continue treatment as directed because…
It simply could be that the treatment coincides with your seasonal hair loss.
Secondly, increased autumnal shedding may exacerbate any existing hair loss conditions.
As a result, you have to look at the positive way that the increased autumnal shedding might be even worse if the hair loss treatment had not been started or introduced.
A good hair health practitioner should also discuss the subject with the patient preceding treatment initiation to avoid unnecessary patient anxiety in later days.
Lastly, as an interesting side note, I came across a paper published by a team of Iraqi researchers. They found that seasonal hair loss in the Iraqi (Northern hemisphere) population occurs in late April / May instead of October/November like in other European countries.
In my own clinical experience in Australia, I have found that many of my Muslim patients, especially women, suffer from increased autumnal hair shedding (in May) exacerbated by the fasting practice soon after Ramadan (April 1-May 1). So that may be why the result of the Iraqi study is different.
Please contact us with any questions or queries regarding this blog or if you would like us to make our references available to you.
Activance Clinic offers specialised, truthful, independent advice, health perspectives inside and outside of orthodox medicine and treatment plans if requested for all hair and scalp concerns as well as other degenerative health issues.