There are two things I’ve believed since I was a teen: First, that air drying is the healthiest way to dry my hair; Second, that moisture is the only thing my strands really need. Throughout my life, I’ve done my best to avoid the blow dryer, for fear that it would make my curly hair frizz out (even more than it usually does). I’ve also avoided products that contain protein, worried that they would make my curls crunchy and stringy. The styling results have been mixed — from amazing to terrible hair days — but I didn’t think much of it until recently, when I came across the term “hygral fatigue.” As it turns out, my hair has not been at its healthiest, and it’s likely because I’ve been air drying and overly moisturizing it.
Don’t have time to read the details? Here’s the most important stuff: Hair that’s regularly overly moisturized can develop hygral fatigue, a form of permanent hair damage. This results in dull, brittle, tangled, frizzy, and gummy-like hair. To prevent it, you’ll need to a) use products with at least some protein on wash days; b) try a pre-shampoo to protect hair in the shower; c) possibly use a hairdryer or fan instead of air drying. Read on to fully understand the concept of hygral fatigue and how to treat your hair based on your hair type.
What is hygral fatigue?
“Hygral fatigue is essentially a type of hair damage that is brought on by excessive expanding and contracting of the hair follicle,” says Jessica Shultz, salon owner and stylist at Twisted Scissor’s Salon in New York. “It’s caused by over-moisturizing. The moisture is what causes the follicle to expand and contract more often than [it’s] meant to.”
“This repeated cycle of wetting and drying, which is also swelling and shrinking the hair shaft, [as well as] lifting of the hair cuticle, can cause cracks in the hair cuticle,” explains Mell Guido, stylist, curl specialist, and educator in a YouTube video. “The hair cuticle [is the] roof over the house, or the hair strand. [The cuticle] protects all of the contents on the inside and also gives the hair its outer appearance.” So, washing and drying your hair too often can cause hygral fatigue (moisture overload isn’t the only culprit).
Guido says hygral fatigue explains why the longer our hair gets, the dryer our ends get: “It’s simply because [your ends] have been on your hair for so long … They’ve been through so many cycles of that wet-to-dry process, and over time, [that] increases the porosity on your ends.”
What is hair porosity?
“Porosity” refers to how well your hair absorbs and maintains moisture. The health of the cuticle determines how easily moisture passes in and out of your strands. According to Guido, having cracks and holes in your cuticle (remember: that’s the protective outer layer) leads to an increase in hair porosity — which isn’t something you want.
There are three types of hair porosity: low, medium, and high. (Professional hair colorists grade porosity on a level from one to five, but to make things easier to understand, most sources use three general porosity types.) Low porosity refers to strands that don’t easily absorb moisture. Medium porosity refers to strands that more readily absorb moisture — this level is usually the easiest to style and take care of. High porosity refers to strands that easily absorb a lot of moisture. There are three factors that can increase your hair porosity:
- Chemicals, like dyes and bleach
- Intense heat, like curling irons and flat irons
- Repeatedly over-moisturizing your hair, by either using products that are too high in moisture or letting your hair stay wet for long periods of time.
How do I know if my hair is low, medium, or high porosity?
Many sources recommend the hair porosity water test to determine your porosity level, which involves taking a strand of your hair and dropping it into a glass of water. According to the water test, the hair will float if it’s low porosity, sink midway if it’s medium porosity, or sink to the bottom if it’s high porosity. However, this test is inaccurate.
“This is not going to give you accurate results,” says Guido. “Depending on its texture, your hair will have a different molecular weight and will react differently in the water regardless. So many other things can cause your hair to sink or to float in water.” To really determine your hair porosity, try the method below.
Spray a section of your hair with water and observe it.
First, make sure your hair is clean and has no product on it. Then, spray down a section with water and look for signs of low to high porosity:
- Low porosity: Water beads on the surface and takes a while to sink in.
- Medium porosity: Water may bead slightly on the surface, but sink in easily.
- High porosity: Hair immediately soaks up the water with no beading.
An extra tip: Think back on your hair treatments. How often have you dyed or bleached your strands? The more you chemically alter your hair, the more porous it is. And lastly, don’t rely on hair texture to determine porosity. Some sources claim that smooth hair indicates low porosity while rough hair indicates high porosity. However, it’s possible to have naturally-smooth hair that is now bleached and more porous. It’s also possible to have naturally rough-textured hair that barely allows any water in (like mine).
Why is hair porosity important to understand?
If you’re worried that your hair has hygral fatigue, you’ll need to know the best way to treat it. Treatment methods vary depending on porosity. Low porosity strands, for example, need products with high moisture and low protein. Medium porosity hair generally needs equal amounts of protein and moisture, and high porosity hair needs mostly protein and a little moisture. (Of course, this can change depending on weather and other factors, like the hardness of your water.)
How do I know if I have hygral fatigue?
While everyone’s hair is different, hygral fatigue tends to create strands that are (according to Guido):
- Extremely soft
As Shults points out, high porosity hair is the most susceptible because it absorbs the most moisture. Worried that you over-moisturize? Don’t panic — while moisture overload can lead to hygral fatigue, a few high-moisture days aren’t going to permanently ruin your hair. The true damage comes when your hair is repeatedly over-moisturized.
How do I fix hygral fatigue?
Unfortunately, true hygral fatigue cannot be fixed. “If you suspect your hair has hygral fatigue, the only thing to do is prevent further damage,” says Shults. “Any hygral fatigued hair will remain damaged until you grow out future healthy hair and cut away the damage.”
The good news: Most hair is simply over-moisturized, not permanently damaged. In this case, “you want to immediately start treating your hair much more delicately,” says Shults. “This includes being very gentle in the shower when cleaning your hair as well as when you towel your hair dry.” Below are a few other tips for preventing hygral fatigue.
Wash your hair less frequently.
“You really want to prevent how much your hair is getting wet — how much it is going from wet to dry — and also how long it is staying wet,” says Guido. Also, washing your hair too often can strip important oils from your scalp and leave your hair too dry. If you have straight hair that gets oily quickly, try washing your hair two to three times weekly. If it’s curly or on the dryer side, try washing it once a week or even less often than that.
Air dry or blow dry depending on your hair type.
If you have very thick hair that takes a long time to dry (like mine), pick up the blow dryer. Concerned about radiation? Use a low-EMF dryer and hold it further away from your head. This is made easy by a diffuser attachment. Otherwise, try sitting in front of a gentle fan or air filter, and flip your hair frequently from one side to the other.
Don’t have thick hair? Air drying may be the best option. “I would not recommend using a blow dryer, as this will cause more expanding and contracting of the follicle,” says Shults.
Regardless of your hair thickness, use lightweight styling products if you air dry. For instance: Try a lightweight leave-in conditioner instead of cream, and a runny styling gel or foamy mousse instead of a thick, sticky gel. Do your best to use less product, too, to help your hair dry more quickly. (Use a hairbrush designed for wet hair to evenly distribute the product so you can use less of it.)
Use a little protein, and try a pre-shampoo.
No matter your hair porosity, Guido recommends that you use products with at least a little bit of protein. “Everybody needs protein,” she says. “Even if you are the lowest of the lowest of porosities and you say your hair allows no moisture in, you want protein in your hair.” Don’t know what to buy? Look for products that say “strengthening” on the label.
And before you step in the shower, try coating your hair in a pre-shampoo or a little oil (such as coconut oil) before you wash it. “Studies have shown that the fiber swelling of the hair was reduced when the hair was pre-treated with things like coconut oil,” says Guido.
Since I’ve stopped washing my hair so frequently and added a conditioner with protein to my routine, I’ve seen a noticeable improvement. I’ve also scheduled my next salon appointment to get my dry ends chopped. My takeaway? Moisture is very important, but it isn’t the whole story. There’s a lot more to hair care than what meets the eye, but following a healthy routine will help maintain longevity.