By the numbers
First, let’s get a bead on “normal” hair loss. We turned to Pascale Mora, in charge of Scientific Communication at Vichy for a by-the-numbers perspective. “At any given moment 90 to 95 percent of the hair on a healthy human scalp is in growth phase,” she informed us. “The remaining 5 to 10 percent is at rest – and ready to shed.” Pascale hastens to reassure: “Luckily, each hair follicle is independent so that we don’t lose the whole lot at once!”
Still, we all lose some strands each day. Just how many can we spare? Pascale Mora: “Fifty to about 100 hairs a day is normal. Don’t worry if you find a few strands in your hairbrush. On the other hand, if your pillow is covered with hairs when you awake or if you see a handful in the shower drain, you may be facing excessive hair loss.”
Owing to the influence of seasonal sun exposure on steroid hormones, all mammals – including us humans – tend to shed more hair in the autumn. And testosterone, the male hormone that makes men’s hair grow faster than women’s, also contributes to a higher daily hair loss.
Hormonal fluctuations induce the significant hair loss often experienced by new mothers. Strands which would otherwise have fallen out over the preceding nine months are kept in place by pregnancy hormones. When oestrogen levels return to normal after delivery, those hairs lose their hormonal anchor and fall away. The situation is temporary, though, and usually rights itself within a few months.
A physical or emotional shock to the system – a death, divorce, major surgery – can trigger sudden hair loss three to four months after the event. Again, hormones are the culprit. But as body and mind recover, the hair also resumes its usual cycle.
Normal… or not
Even if you shed what seems to be rather a lot of hair, so long as healthy growth continues and hair density remains stable, there is no cause for alarm. But perceptible thinning or encroaching bald spots are signs that you that should seek the advice of your pharmacist. If the fall-out is sudden or severe, a consultation with a dermatologist is in order. Your dermatologist can detect underlying problems or pathologies – iron deficiency, thyroid or hormonal issues, side effects from certain medications – which may contribute to hair loss.