Is It True That Your Hair Changes Every 7 Years?

Photo: Maarten Rutten/EyeEm/Getty Images

I have to admit, I’m not much of a believer in stability. As a millennial coming of age in the Obama-Trump transition, I can name only a few constants that have endured: the hardness of rocks, the liquidness of water, and up until recently, the chaos of my hair. Ultrathick, pouf-y, and prone to frizz, it’s always refused to be tamed by weather or flattening irons, and most “smoothing” products have sat on top of it in a greasy film. Following a decade-long battle that lasted throughout my adolescence, I ultimately gave in to the wild beast atop my scalp, wise to the understanding I could never change its nature.

Until one morning in March, when I looked in the mirror and saw the miracle. There it was, my hair — only it wasn’t my hair. It had gone from looking like a thundercloud to heavy rain. Sleek, mahogany curtains framed my incredulous expression as I stared into the face of the girl I had always wanted to be: myself, but with manageable hair. This was a fluke, I decided — the elusive “good hair day” phenomenon I’d always heard about but never experienced.

And yet it persisted. For the next week, I lived with bated breath from shower to shower, wondering when the next air-dry would return me to my old “before”-picture hairstyle. It must be a climate thing, I reasoned (I was on a different continent at the time), or maybe a dietary thing (I’d been eating more chocolate). But since then, I’ve been on two other continents and the industrial-size blocks of Cadbury have disappeared, but the sleekness — though it’s a bit less pronounced — is still there. My life over the past few months has been so entirely hectic, in fact, that my hair’s transformation has been its only constant.

I began telling my friends about this weird new development in the hopes that someone might have an explanation. Eventually, I struck gold with my cousin: “Oh, well, your hair changes texture every seven years,” she told me. “You know that.” What? Did I? Was this some CosmoGirl wisdom I’d failed to encounter?

An initial Google seemed to confirm it. But still, the internet isn’t exactly a foolproof source of information when it comes to information about health or the body, and I wasn’t ready to accept my cousin’s explanation quite yet. Seeking deeper answers, I contacted several trichologists, people person who specialize in the treatment of hair and hair follicles. (As I soon learned, the term has also largely become synonymous for “hair loss specialist” — it seems the vast majority of people who seek out trichologists are losing their hair, not having it magically smoothed overnight by some ultrakind fairy godmother.) I was curious: What was the scientific explanation for what had happened to me? And: Does human hair really reinvent its style every seven years, like the cellular version of Madonna?

The first answer I received was from physician Carlos Wesley, a hair transplant surgeon and trichologist based in New York. Wesley greeted me warmly, then asked his first question: “Is there any chance that you’re pregnant?”

“Hmmm,” I said aloud. I’m not. But what did that have to do with my hair?

He explained: “Generally, as estrogen levels rise — such as during pregnancy, or starting any therapy that may cause a steady increase — curly hair can become more straight, shiny, and easier to style.” This occurs because the hair follicle gets slightly sturdier, and thus less prone to frizzing out or curling. Many pregnant women notice that their hair gets sleeker and smoother; this is probably why.

As for the seven-year-cycle theory put forth by my cousin, Wesley had his own take. Our hair grows in “bundles,” he explained, with a single follicle containing multiple strands of hair. Every seven years or so, those bundles reset — but gradually, they lose strands, explaining the thinning hair that some women notice as they get older.

It could be that for my massive forest of hair, a few felled trees isn’t such a bad thing: As Liz Cunnane Philips, a trichologist at Philip Kingsley in New York, noted: “If we start with an abundance of volume, some lessening of that volume can be welcomed as it results in sleeker, smoother hair.”

Philips also pointed out that my “sudden” hair change is probably due less to the actual pace of the shift and more to my own powers of observation. “All hair texture types have the potential to change,” she wrote in an email. “However, the follicle will influence the hair that is growing as we speak, not the hair that is several months or even years old, which is what you are seeing in the mirror.”

David Kingsley, president of the New York–based World Trichology Society, echoed Wesley’s comments about hormonal changes. However, he also suggested that what I was seeing might be due in part to shifts at the genetic level. As we get older, certain DNA “switches” get turned on and off, particularly in the hair-producing follicle cells. One common example of this in men is the increased sensitivity of follicle cells to the hormone Dihydrotestosterone (DHT), leading to the condition known as male-pattern baldness. As for the specific gene at work in my case, though, Kingsley was at a loss.

So did I find my answer? Not quite. The reasons for my hair’s transformation, much like life itself, are impossible to control. Perhaps trichologists will one day unlock the key to textural changes in hair, like the one I experienced, and turn it into a technology we can use. Until then, I’ll revel in my newly manageable tresses, knowing just how ephemeral they might be.

Is It True That Your Hair Changes Every 7 Years?