It is not that your hair got worse. It is that it started behaving like somebody else's.

This is the complaint we heard most often and with the most feeling: hair that was straight and glossy for forty years going coarse, wavy, frizzy — sometimes with a whole different-textured layer underneath that nobody can explain. "Someone else's hair growing out of my head" is how one woman put it. Another: "menopause hair is drunk." A third described the texture of Velcro.

What is happening is real and it is physical. Falling oestrogen changes the fibre itself — the shaft comes through drier, the cuticle sits rougher, and rough cuticle is what frizz actually is. Light hits a rough surface and scatters instead of reflecting, which is why the shine goes first and why you notice it before you notice anything else. Shine is the thing women mourn most specifically, and it is not vanity. It is the visible signal that your hair has changed without your permission.

The cuticle is the bit you can do something about. Hydrolysed keratin is small enough to settle into the gaps where keratin has been lost; hydrolysed silk lies along the shaft and gives slip. Between them they get the cuticle lying flatter, and a flatter cuticle reflects light again. That is the whole mechanism, and it is not complicated.

It will not put your hormones back. It will not give you your twenties hair. It will make the hair you have now feel smooth when you run your hand down it, and it will catch the light again — which, going on what women actually told us, is most of what you wanted.