Study Investigates How Much Stress Causes Permanent Hair Damage

Anyone with a professional interest in hair loss and hair care is concerned not only with the causes of various conditions, but the actual structure of human hair, too.

A new hair study by the University of California, San Diego, was inspired by a growing appreciation for how natural organic materials often have near-miraculous properties. The team set out to assess just how strong human hair is and how much stress could it endure before it suffered permanent damage. This does not mean the same types of stress that can lead to thinning hair, but instead it refers to how much physical impact can withstand before permanent damage is caused.

The research team states that hair has a strength-to-weight ratio comparable to steel, and that it can be stretched to 1.5 times its original length before breaking. Armed with this knowledge, the scientists set out to “understand the mechanism behind this extraordinary property.”

Diagram Showing the Makeup of Human Hair

Nanoscale level

Researchers zoomed in on hair at a nanoscale level to see how a strand of human hair behaves when it is stretched. They discovered that hair behaves differently depending on how fast or how slowly it is stretched. The more rapidly hair is stretched, the stronger it is. “Think of a highly viscous substance like honey,” said Marc Meyers, a professor of mechanical engineering at the University’s Jacobs School of Engineering. “If you deform it fast it becomes stiff, but if you deform it slowly it readily pours.”

This is not dissimilar to an existing man-made British product named D3o, which is already used in protective wear and some body armour.

An article on the University’s website explains that hair consists of two main parts the cortex, which is is made up of parallel fibrils, and the matrix, which has an amorphous (i.e. random) structure. They say that the matrix is sensitive to the speed at which hair is deformed, but the cortex is not. The combination of these two components is what gives hair the ability to withstand high stress and strain.

Interestingly they found that structural transformation is reversible to a degree. A small amount of strain meant that hair could recover to its original shape, but too much stretching makes the changes irreversible.

Hair at different temperatures

The scientists also stretched hair at different temperatures and humidity levels. They found that damp hair boosts its stretching capabilities by an additional 50 per cent or so, while hair heated above 60 degrees Celsius breaks faster. Permanent damage was also seen on unstretched hair above 60 degrees.

The findings show that while strong, hair can certainly be delicate, too. Brittle hair and hair breakage are oft-seen results of over-heating: the makers of GHD hair straighteners recently warned people not to over-heat their hair, while American actor and pop star Zendaya spoke to the press about the woes she suffered from excessive use of heat-styling products. “I was only 14 years old and didn’t know how to protect my hair,” she said, adding that it took more than two years to grow it back after it had become damaged.

Intense levels of heat from styling tools or even a prolonged blast with a hairdryer can strip moisture from the hair, and hair breakage can ensue. This happens when hair snaps along its shaft something people often observe as frizzy, thin hair.

In addition to heat damage, hair breakage can also be caused by chemicals - such as over-bleaching or using chemical relaxing or perming solutions the hair - or from using hair extensions.

Damage to the shaft

While this type of breakage is not actually a hair loss condition as it involves damage to the shaft rather than the hair follicle, it can certainly make an existing condition appear worse. Women who are losing hair to the genetic condition Female Pattern Hair Loss, for example, would likely notice their hair looking thinner still if breakage were present.

Luckily, Female Pattern Hair Loss treatment at a specialist clinic can help address both the reasons for the hair fall and the damaged hair. Treatment courses at Belgravia are purpose-designed for each client and, in cases such as the one described above, would typically include topical applications of high strength minoxidil, and growth boosters such as Hair Vitalics, a food supplement containing a proprietary blend of vitamins, minerals, botanicals and amino acids. These, along with recommended shampoos and conditioners plus clinical therapy treatments can benefit scalp health as well as the hair.

Hair breakage can, of course, be avoided by reducing heat styling, and it can be minimised by keeping exposure to the heat source to a minimum. Allowing hair to air-dry before finishing off with a blow-dryer, for example, is a top tip that can reduce hair woes.