Beauty sleep is a real thing.

No, really – it's not just a tag line to sell products. When we sleep, our cell and skin literally renew themselves, which is why a lack of sleep can literally make you look all sorts of wrecked and, well, tired. The beauty market has understood this, and we are forever inundated with skin products aimed for use during the night, designed to be applied before bedtime and left working all night, allowing the active ingredients to penetrate into our skin and do their job. And now, guys – now the experts at Kérastase have realised that you can do the same with hair care products, and have developed a serum designed to be left in your hair overnight – giving your locks a serious dose of moisture and nutrition – all while you are snoozing away. The Kérastase Nutritive 8H Magic Night Serum is a leave-in product that will transform dry, lifeless locks into a soft, glossy mane by giving a serious boost to all hair types with Iris Root extract and a blend of five vitamins including vitamin E. Working through the night while you sleep, this non-greasy hair serum delivers intensive overnight nourishment, and my hair, which tends to be a tangled mess when I wake up in the morning, seriously looked so much smoother and softer after one night using the serum. I was a bit sceptical at first, worrying that not only would my fine-ish hair be weighed down by a thick and heavy serum, but that also, my pillowcase would be destroyed in the process. I am happy to report that neither was an issue, which the milky-gel like serum melting into my hair almost instantly, and my pillow was intact the following morning too. In fact, I would even say that the non-greasy serum lessened the friction between my hair and the pillow, meaning less moisure loss and less frizzy hair. What did happen, was that I woke up with super-silky hair, that was easier to comb out than it has in forever, and that really made my hair look seriously glossy – reality star hair, one might even say. Pumping two-three pumps into my hand, I distributed the serum into my hair, focusing especially on my poor, negelected dry ends. Then voila – I hit the hay, and let the serum's clever ingredients get to work. The best bit? That there was no rinsing to be done the next morning, and my hair was just ready to be styled once I woke up. At €39, the Nutritive 8H Magic Night Serum doesn't come cheap, but if you want to give your hair a little TLC, and save your dry, brittle ends, I think this is one purchase you will not regret making.