If you have any questions, you are always welcome to contact us. We'll get back to you as soon as possible, within 24 hours on weekdays.
Shipping Information
Free shipping in Canada on orders $150+ and to the U.S. on orders $200+
Returns & exchanges
To learn more about our Return & Exchange Policy, click here.
Support?
Our customer support team is available and ready to assist with any questions or concerns. Whether it’s about your order, products, or just some haircare advice—we’ve got you covered.
Overnight Youth Serum by Kérastase is a powerful age-corrective leave-in treatment designed to work while you sleep, reversing visible signs of hair aging by morning.
Infused with Pro-Xylane™ and Ochrophyta Algae, this advanced overnight serum delivers concentrated actives deep into the hair fiber to restore vitality, strength, and youthfulness—effortlessly, with just one pump.
Why you'll love it:
As hair ages, it can lose density, shine, and smoothness. Overnight Youth Serum targets these concerns at their source, replenishing the hair fiber during the natural nighttime renewal cycle.
Pro-Xylane™: A green-chemistry molecule renowned for its powerful anti-aging properties, helping to reinforce and densify the hair fiber
Ochrophyta Algae: A rare, bio-sourced deep-sea algae known for its regenerative and revitalizing benefits
Its ultra-light, quick-break texture melts instantly into the hair, leaving no residue—only soft, supple lengths infused with the iconic Chronologiste fragrance, transforming your nighttime routine into a luxurious ritual.
Who is it for:
Ideal for hair showing signs of aging, including:
Loss of thickness
Frizz and dryness
Dullness
Lack of volume and vitality
Perfect for anyone seeking visibly younger-looking hair by morning.
Visible results after just one night
+5.7% thicker hair fiber*
–66% frizz*
+32% shine*
+92% stronger hair*
77% say hair feels revitalized**
*Instrumental test after 1 use of Overnight Youth Serum **Consumer test after one application of full Chronologiste routine (Bain + Masque + Overnight Serum)
Usage
Apply to dry or damp hair before bedtime.
Dispense one pump into your hands and distribute evenly through mid-lengths and ends.
Leave in overnight. No rinsing required.
Wake up to hair that feels fuller, smoother, stronger, and visibly healthier.
