Dryer, straightener: 4 gentle habits

You’ve just run the straightener through your hair, section by section, like every morning. Tidying up, you notice little bits of hair on the basin, barely three or four centimetres long. There are more in the brush, and a few short, frizzy ones sticking up along your parting. Are you losing your hair?

Not necessarily. Those little bits look more like breakage. And breakage, unlike hair loss, depends largely on what you do to your hair.

Broken hair or shed hair?

Everyone loses between 50 and 100 hairs a day, and that’s nothing to worry about⁸. These are hairs that have reached the end of their cycle: they come out with their root, which is shaped like a little club⁷. We go into the detail in how many hairs you lose a day.

A broken hair snaps partway along. There’s no root at the end: it’s cut clean or frayed, and often shorter than a shed hair. The root stays put and the hair keeps growing from the follicle.

To tell them apart, pick up a few hairs from the basin or your brush and look at the ends. Lots of short pieces with no root and split ends: the fibre is suffering. Long, whole hairs with their root: that’s shedding, and styling usually has nothing to do with it.

What heat does to hair

Hair is protected by a layer of scales, the cuticle, a bit like tiles on a roof. Heat lifts and cracks it⁵. The hair turns rough and dry⁵, and damaged, fragile hair tends to break⁴.

There’s a more dramatic version, which dermatologists call bubble hair. When wet hair is heated hard, the water inside turns to steam and blows bubbles through it. The hair becomes a kind of sponge, dry and brittle. Hair dryers running at 175°C or more, or curling tongs at 125°C held on for a minute, are enough to cause it⁶.

A team in India described a 22-year-old woman who came in with dry, very fragile hair that had started two weeks earlier. She had used a straightener on wet hair twice in the past month. Her hair was broken unevenly, but it didn’t pull out easily: the roots were holding firm⁶. It’s a single case, but it shows how little it can take. The advice given: stop using so much heat and cut off the damaged part⁶.

Hair dryers: distance matters

In 2011, Korean researchers washed and dried hair tresses once a day for 30 days, in different ways: in the open air, or with a dryer at 15, 10 or 5 cm. Each distance came with a temperature and a drying time: one minute at 15 cm, fifteen seconds at 5 cm. The damage was then examined under the microscope⁵.

The closer the dryer, the more the cuticle was damaged: a few cracks at 47°C, more cracks and lifted scales at 61°C. At 95°C and in the open air, the hair colour lightened after just 10 sessions⁵. In no group was the inside of the hair affected⁵.

The most surprising result concerns air-drying. The tresses took over two hours to dry, soaked through, and they were the only ones where the “cement” that binds the hair cells together was damaged⁵. The authors conclude that a dryer held at 15 cm and kept moving does less damage than drying naturally⁵.

The study has its limits: cut tresses rather than hair on a head, and nothing on hair loss itself. The American Academy of Dermatology (AAD) is more cautious. For fragile hair, it recommends the lowest heat setting and air-drying when you can¹. Letting hair partly air-dry before styling, and blow-drying fewer times a week, also limits the damage³.

Straighteners and curling tongs

Straighteners and tongs sit right on the hair. The AAD gives clear guidelines: use a straightener on dry hair, on a low or medium setting, no more than every other day. Curling tongs should stay in place for only a second or two³.

If your hair is already thinning or fragile, it goes further: keep tongs, straighteners and hot combs for special occasions¹, or aim for once a week or even less⁴. Thinning hair is fragile and easily damaged¹.

And never on wet hair, not even slightly damp. That is exactly what causes bubbles in the hair⁶.

4 gentle everyday habits

1. Set the dryer to the lowest heat¹, keep about 15 cm between the nozzle and your hair, and keep it moving⁵.
2. Use the straightener and tongs less often, always on fully dry hair, on a low or medium setting³.
3. Wrap your hair in a microfibre towel, without rubbing, so it dries faster¹. Rubbing wears down the hair surface, especially when it’s wet⁵.
4. Detangle gently with a wide-tooth comb, just enough to style, without tugging⁴. Wet hair breaks more easily under a brush; for curly or tightly coiled hair, though, the AAD advises detangling while damp³.

The old advice of a hundred brush strokes every night does the opposite: we explain why in our article on common misconceptions.

When breakage turns into hair loss

Heat mostly damages the hair shaft. Other habits, though, can reach the follicle.

The first is chemicals. According to the AAD, colouring, perming or relaxing your hair can damage it and, over time, lead to hair loss². Its advice: stop doing these at home and go to a salon that specialises in them¹.

The second is styles that pull. A tight bun, ponytail or braids, worn often, can cause traction alopecia, hair loss that can become permanent¹. A destroyed follicle can’t grow a hair again². The signs and how to prevent it are covered in our article on styles that pull.

Finally, if what you’re picking up is whole hairs with their roots, lots of them, for weeks, the straightener probably isn’t to blame. Look instead at the most common causes of hair loss. And no, washing your hair doesn’t make it fall out: we explain why in our article on hair washing.

Seeing whether your hair breaks less

Hair grows slowly. After turning the heat down, it takes weeks for the broken bits to be replaced by healthy lengths, and you won’t see it from one day to the next.

The simplest way is one photo a week, in the same conditions: your parting from above, where the short broken hairs stick up, and your lengths, dry and unstyled. After a few months, you can see whether the frizz along the parting is settling down and whether your ends are holding up better.

Calvap helps you frame every photo the same way, with your previous photo shown as a faint overlay. You log your new habits in your journal, and the timeline shows you, week after week, what difference they make.