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Culture & Society
A study finds that letting hair rest for two hours after heat styling can significantly reduce breakage and restore strength.
Giving hair a break after using a flat iron can dramatically cut down on breakage and splitting, according to new research. The hair needs time to recover its moisture and strength after being exposed to high heat.
Researchers explained that heat temporarily weakens hair fibers, making them more brittle and prone to snapping when combed immediately after straightening. This effect is not permanent, however, as hair can gradually heal if left alone before any styling or brushing.
The study found that letting hair "rest" for two hours after using a straightening iron allows it to regain nearly all of its original strength. Even a 30-minute wait can significantly reduce damage, the researchers noted.
Published in the Journal of the Mechanical Behavior of Biomedical Materials, the research links the damage primarily to moisture loss from heat, followed by gradual reabsorption of moisture from the surrounding air.
To understand how breakage occurs, a team from the University of Dublin developed a device that simulates combing tangled hair. They tested various hair types, including straight, curly, treated, and damage-prone hair.
Professor David Taylor explained that individual strands are very thin and flexible, so they tangle easily. When combed, knots travel along the strand to the tips, creating enormous pressure that can lead to breakage or snapping.
Experiments revealed that hair exposed to 150 degrees Celsius became much weaker than natural hair, with its ability to withstand repeated stress dropping sharply. The results also showed that strong hair resists breakage longer, while internal cracks appear early in more brittle hair.
Although curly and wet hair were affected by heat, they managed to recover a large portion of their strength within two hours.
The researchers confirmed that moisture in the air helps dry hair gradually rehydrate, explaining why its condition improves after a pause from heat styling. Professor Taylor noted that some people naturally have more breakage-prone hair, but overuse of dyes, straightening, and heat treatments increases damage for everyone.
He added that regular trimming helps prevent cracks from traveling along the strand, pointing out that long hair is more susceptible to breakage due to weaker tips. Previous research from Harvard University found that the best way to detangle hair is to start combing from the tips and work upward, as this reduces stress on the strand and limits breakage.
