This article was reviewed by Knox Beasley, MD.
Your dog or cat might lose some fur when the weather heats up, but do humans shed hair in the summer? Is seasonal hair shedding a real thing?
In short, yes. You might experience seasonal hair loss at certain times of the year. Seasonal changes can affect the hair growth cycle, possibly causing some strands to fall out prematurely.
Although there’s a lack of research on seasonal hair shedding in humans, there’s pretty solid evidence that it can happen. Let’s take a look at seasonal hair loss and discuss how to stop seasonal hair fall.
What Is Seasonal Hair Shedding?
Seasonal hair shedding is when you lose hair at different times of the year, potentially due to changing outdoor temperatures, humidity levels, or sunlight exposure. These environmental shifts can affect your skin and, thus, your scalp, which might lead to extra hair fall.
How Seasonal Changes Affect the Hair Growth Cycle
Depending on which experts you ask, hair grows in three or four phases:
- The anagen phase (growth phase), which can last years
- The catagen phase, where the follicle transitions to the telogen phase
- The telogen phase, also called the resting phase, when it stops growing
- The exogen phase, when hair falls out
After the exogen phase, a new hair will start growing out of the follicle, and the growth cycle begins again.
Every single strand of hair is in a slightly different part of this cycle at any given time, which is why you don’t go entirely bald once every few years.
But every so often, environmental conditions (among other factors) might shift more hair follicles into the resting and shedding phase. This is called telogen effluvium, a temporary type of hair loss caused by a shock to the system.
Though telogen effluvium is usually caused by issues like illness, severe stress, or significant blood loss, it could also be due to changing seasons.
When Does Hair Shed the Most?
Seasonal hair shedding is when you lose hair at different times of the year, potentially due to changing outdoor temperatures, humidity levels, or sunlight exposure. These environmental shifts can affect your skin and, thus, your scalp, which might lead to extra hair fall.
To understand seasonal hair shedding, you need to first understand the hair growth cycle.
Your furry friends tend to shed hair in summer and grow more in winter. But when is shedding season for humans?
It’s hard to say. Some people may lose hair during warmer times of the year, while others find that the cold triggers excessive hair loss.
Seasonal hair loss is a difficult idea to pin down, though several studies have tried. For instance, one 2009 study looked at hair loss in more than 800 otherwise healthy women and found that:
- Hair growth and loss patterns have seasonal behaviors
- More hairs are in the resting phase of the growth cycle during the summer
- Spring also sees a higher number of resting hair follicles
- The fewest follicles are in the resting phase during the winter
What this means is that you might shed more hair in the summer (or a particularly hot spring) than in the winter.
Why Does Hair Shed More in Warmer Weather?
Why this happens remains a mystery. One explanation has to do with the number of daylight hours per season.
Some experts think low-daylight seasons (late fall and winter) may keep hairs in the telogen phase longer, which would slow down shedding. And then a return to more daylight hours in the spring and summer speeds up the shedding of club hairs (those preparing to fall out).
This wouldn’t suggest that your hair cycles are speeding up or that more hairs are going into the telogen phase — just that more hairs in the telogen phase are disconnecting from your scalp in warmer weather.
However, sometimes the very opposite happens.
For example, alopecia areata may be triggered by the cold, according to the American Academy of Dermatology. Showing up as patchy hair loss, alopecia areata is caused by an autoimmune reaction against hair follicles.
A 2018 paper published in the Journal of the American Academy of Dermatology looked at seasonal patterns in flare-ups of alopecia areata in over 300 children. It found that flare-ups most often coincided with colder months and happened less frequently in warmer seasons.
The researchers pointed to many unanswered questions about what triggers flare-ups. Also, the study was retrospective, meaning participants reported previous hair loss they experienced. So follow-ups would be needed to see if there was a causal relationship between seasonal changes and shedding — or if it was simply a coincidence.
Is Seasonal Hair Loss Common?
Collective data suggest summer is when you’re most likely to shed or lose additional hair. But just how common is this?
How common seasonal hair loss is depends on your criteria. For instance, experts believe a version of seasonal telogen effluvium explains why most mammals shed their winter coats — which would make summer hair shedding pretty common, as pet owners know.
Researchers are slightly less clear on whether the impact is similar in humans, but many think it “probably” plays a role.
Of course, that assumes a person’s seasonal hair loss is related to normal shedding cycles. Excessive shedding and long-term hair loss are different.
How to Treat Seasonal Hair Shedding
Here’s the thing about telogen effluvium: It typically resolves itself. But there are still ways to speed up the regrowth process while promoting healthy hair growth.
When caused by bodily traumas like surgery, chronic stress, or severe illness, telogen effluvium usually sets in two to three months after the event and lasts roughly six months before things begin to normalize on their own.
Can’t wait six months? Here are a few ways to treat seasonal hair shedding:
- Try minoxidil. This over-the-counter hair loss treatment can be applied directly to the scalp. It increases blood flow to the area and stimulates hair follicles to enter the anagen phase.
- Eat a balanced diet. Nutrient deficiencies can lead to hair loss because your body needs enough nutrients to grow healthy hair cells. So make sure you get plenty of vitamins, minerals, and protein through whole foods.
- Consider hair-growth supplements. If you have a nutrient deficiency you can’t correct with food, try a supplement containing nutrients like biotin and vitamin D.
- Be gentle on your hair. Avoid extremely tight hairstyles, constant heat styling, and brushing your hair too often — these can cause breakage and strain your hair follicles, potentially leading to a condition called traction alopecia.
- Keep your hair clean. Volumizing shampoo and conditioner might help your hair look and feel thicker.
Conditions like alopecia areata, however, may require serious treatments. You might need prescription hair loss medication or in-office procedures with a dermatologist.
It’s important to talk to a healthcare professional about your hair loss — getting an accurate diagnosis is the first step in taking charge of your hair health.
Seasonal Hair Shedding: The Big Picture
Seasonal hair loss might get better on its own. If you have some hair fall or thinning hair in the summer, it may very well just be due to natural seasonal changes rather than a significant problem or disorder.
Here’s what to remember:
- Seasonal hair shedding doesn’t always happen in the summer. Though you might shed more hair in the warmer months, cold weather could trigger hair loss conditions like alopecia areata.
- There may be ways to reduce seasonal hair shedding. Hair loss treatments like topical minoxidil could stimulate hair regrowth. You can also support healthy hair growth by eating a balanced diet and taking supplements.
- Consulting a professional should be your first port of call. Nothing beats expert medical advice! A healthcare provider can diagnose the cause of your hair loss and suggest treatments.
Seasonal shedding may be nothing to worry about, but it’s still best to talk to a healthcare professional if you have concerns. After all, letting time pass is the worst thing you can do if you’re fighting androgenic alopecia (also known as male pattern baldness).
If you’re seeing signs of hair thinning, we suggest a better-safe-than-sorry approach to treatment. With conditions like alopecia areata, androgenic alopecia, and other types of potentially permanent hair loss, being proactive can mean the difference between saving the hair you have and losing more in the meantime.
This article originally appeared on hims.com and was syndicated by MediaFeed.org.
Featured Image Credit: AndreyPopov / iStock.
