Chronologiste Overnight Youth Serum is Kérastase’s night-time treatment for hair weakened by the visible signs of ageing — dryness, dullness, frizz and a loss of body. The texture is lightweight and fast-absorbing, melting into the lengths without leaving residue on your pillow, and it is not rinsed out in the morning.

The formula is built around Pro-Xylane, a bio-derived sugar molecule that supports hair thickness and density, paired with Ochrophyta Algae, a bio-sourced marine extract rich in remineralising actives that helps defend the fibre against daily stressors.

It suits anyone whose hair has become finer, drier or duller over time and who wants a low-effort step that does the work overnight: Kérastase reports less frizz, more shine and stronger, fuller-feeling fibre from the first use.

Apply to dry or towel-dried hair before bed. Distribute one pump evenly through the lengths and ends, avoiding the scalp. Leave in overnight — no need to rinse in the morning.