While you sleep, your skin kicks into repair mode, thanks to a little hormone called melatonin (often referred to as the “sleepy-time” hormone). “Melatonin is critically important for your skin and plays a significant role in skin repair from environmental exposure, UV light, stressors, pollution, and so on,” says board-certified dermatologist Keira Barr, MD, on an episode of Clean Beauty School. “If you’re not resting, you’re not generating that melatonin, and your skin isn’t repairing itself.”
In terms of repair, the skin sees a surge in HGH (human growth hormone) in the nighttime sleep cycle. The release of HGH helps rebuild body tissues and spurs increased cell production to invigorate and rejuvenate the dermis. When you lose sleep, your skin misses out on this important process, which is why your complexion may appear sallow and dull after a night of poor rest.
And if you lose sleep night after night, that deprivation can induce oxidative stress and lower your antioxidant defenses, making the body (and skin) vulnerable to oxidative damage. Not to mention, losing sleep increases cortisol (the infamous stress hormone), which can break down collagen over time—research has demonstrated a link between shut-eye and collagen production2which is why many experts consider sleep a vital part of any “anti-aging” skin routine.
You should also know that the skin is more permeable at night3, meaning it’s much easier to lose significant hydration as you snooze. That’s why you might want to apply heavier, more occlusive moisturizers before bed to prevent precious moisture from seeping out overnight. In that same vein, that permeability makes your skin more receptive to skin care products, which is why you might layer on more intense actives before hitting the hay.