The $60 Hair Serum That Repairs & Softens Strands While You Sleep

The luxe haircare line Crown Affair has always been about intentional minimalism. In 2019, founder Dianna Crown visited a head spa in Shibuya, Tokyo, and was awed by the gentle treatment of the scalp. The ethos was all about nourishing the roots of what’s already there, versus heating and styling the hair into submission. This experience formed the basis of Crown Affair’s approach to formulation and a grounded, less-is-more beauty philosophy. Cohen launched Crown Affair a year later with the hopes of bringing thoughtful, care-centered hair rituals into the home. Now, the brand is introducing a product that arguably simplifies your routine like none other. Enter The Overnight Repair Serum, a strand-healing treatment combining a blend of flax and chia seed extracts (key for strengthening tresses and preventing breakage), shine-enhancing Rosemary Leaf Extract, and the brand’s own heavenly scented, hydrating Tsubaki Meadows complex. The lightweight serum is meant to be applied to the mids and ends of your hair before bed. Let it delicately repair and heal strands while you sleep.

“This formula is a love letter to my sister, who’s been bleaching her hair blonde for over 20 years,” says Cohen. “She’s been asking me for a simplified, powerful solution—something that actually repairs damage in a clinical way and doesn’t require another rinse or extra step. The Overnight Repair Serum is just that: a serum treatment that works while you sleep, so you wake up with healthier, softer, more touchable hair—no rinse required.”

The serum has a fresh feel about it. It’s one of the few leave-in products that I feel safe applying with no fears of transfer on my Cairo-imported Egyptian Cotton pillow cases. (Crown Affair also has a gorgeous silk pillow case to protect your strands.) The scent is the brand’s signature yuzu, bergamot, and lemongrass blend—uplifting, airy, and natural. There’s nothing synthetic about the sensory experience of applying the serum. The texture is as light as the scent and doesn’t weigh down the hair. Most relevant of all, the serum actually has an impact. At a week in, my frail, split-end-filled locks are feeling noticeably softer. I’ve been trying to grow my ultra-fine hair out for years, working my way through deep conditioners, supplements, oils, and all varieties of hair routines, from the basic to the comically complex. I’m cautiously hopeful that my generally brittle, quick-to-shed mane may finally make it to my lower back.

The Overnight Repair Serum is also the brand’s first clinically tested product. It did particularly well in breakage prevention, with testers noting a 75 percent reduction over the course of a month. Perhaps my optimism is indeed warranted. If nothing else, I’m looking at softer, lusher locks and waking up with a gently intoxicating scent I would happily purchase, even without added shine. “From the beginning, Crown Affair has been about helping you repair your relationship with your hair,” says Cohen. “Now, you can actually repair the hair itself, too.”