Hair Dryer VS Air-Drying:Which damages your hair more?The answer may surprise you.

Every time we wash our hair, we face a small decision—

Air-dry

or

Blow-dry?

Some people can't stand waiting for their hair to dry slowly and grab a blow dryer for a quick fix.

Others hold onto the belief that "natural is gentlest," draping a towel over their shoulders, sitting on the balcony, and letting their hair dry naturally while playing on their phones.

Indeed, we've been taught since childhood that air-drying is best for hair, and that blow dryers damage it.

But have you ever noticed that sometimes blow-dried hair looks shinier and smoother, while air-dried hair tends to be frizzier and more prone to split ends? 🤔

This might not just be your imagination.

A study published by a dermatology team at Yonsei University in South Korea has found scientific evidence for these observations.

(Only Koreans, who love their hair so much, would spend research money on this kind of study 🙊)

Our hair has a three-layer structure: the cuticle, cortex, and medulla.

The cortex provides strength and elasticity, while the cuticle offers external protection. Layers of "cuticle scales" stack and overlap like roof tiles.

Cuticle scales are delicate and intolerant to most external forces, including temperature, humidity, friction, UV rays, and air pollution... Shampooing and drying are among the most common daily behaviors that can damage hair.

So scientists decided to study exactly how blow dryers damage hair, and how different temperatures compare in terms of harm.

The study had five groups:

(The blow dryer was set to a fixed 65°C, but the actual temperature on the hair varied with distance. Temperatures were measured 0.5 cm from the hair surface.)

Simulating daily hair washing habits, each cycle was repeated every 24 hours for a total of 30 cycles, after which various professional methods were used to observe changes in the hair.

First, as expected, higher temperatures caused more severe surface damage.

Compared to the untreated group, the 47°C group already showed uneven cuticles, the 61°C group had more obvious lifting and cracking, and the 95°C group suffered the most severe damage, with multiple cracks, holes, and blurred cuticle boundaries.

The 95°C group even showed perforations in the cuticle:

As for moisture content, all treated groups had lower water content than the untreated group, indicating that the shampooing process itself may affect hair moisture. However, after only 30 treatments, the differences weren't yet significant.

So far, everything was following the "script."

But then, things took an unexpected turn!

When researchers looked deeper into the hair's internal structure, they found that only the air-drying group showed damage to the "cell membrane complex" (CMC)—none of the other groups did!

What is the cell membrane complex?

Simply put, the CMC is a key structure located between the cuticle and the cortex. It is rich in lipids and acts like glue, binding cells together, keeping the cuticle and cortex tightly connected, maintaining structural stability, and serving as a barrier.

It's the cement in a brick house, the filling in a 3+2 cookie.

In short, the integrity of the CMC can affect the hair's cuticle tightness, smoothness, flexibility, and resistance to damage.

So the question is: why does air-drying damage this inner layer?

Researchers believe the reason is likely that the hair is "soaking in water" for too long!

At room temperature, natural drying takes two hours. During this extended wet period, moisture penetrates deep into the hair, causing it to swell and leading to damage.

In addition, both the air-drying group and the 95°C group showed signs of color change earlier than other groups.

Fading and yellowing are also signs of hair damage. Researchers reasonably suspect that prolonged dampness is just as harmful as high heat.

Many previous studies have also confirmed that damp hair is relatively fragile and more prone to damage and frizz. 💧💧💧

We always think "natural" is best for our hair. But the truth is, hair's natural state isn't wet at all. It doesn't want to air-dry...

It just wants to dry quickly.

The right temperature + faster drying time = less damage. Whether a blow dryer damages your hair depends on how you use it:

(15 cm is roughly the distance between your thumb and index finger when stretched apart—you can measure it yourself!)

And compared to the simple, rough treatment in the experiment, we have various hair care products and techniques to help reduce cuticle damage and minimize impact on hair.

Here's a complete "step-by-step hair washing tutorial" to help make your hair better and better:

🌀 Before Washing

🌀 During Washing

🌀 After Washing

Share your hair photos and care tips in the comments!

Dr. Dai Ru

PhD in Dermatology

[1] Lee Y, Kim YD, Hyun HJ, Pi LQ, Jin X, Lee WS. Hair shaft damage from heat and drying time of hair dryer. Ann Dermatol. 2011 Nov;23(4):455-62.

[2] Yang FC, Zhang Y, Rheinstädter MC. The structure of people's hair. PeerJ. 2014 Oct 14;2:e619.

[3] Kreplak L, Mérigoux C, Briki F, Flot D, Doucet J. Investigation of human hair cuticle structure by microdiffraction: direct observation of cell membrane complex swelling. Biochim Biophys Acta. 2001 Jun 11;1547(2):268-74

[4] Robbins C. The cell membrane complex: three related but different cellular cohesion components of mammalian hair fibers. J Cosmet Sci. 2009 Jul-Aug;60(4):437-65.

Planning: L | Supervision: Feidi

Illustrations: See captions | Cover image source: Internet

Sharing From: Dingxiang Doctor