Have you ever woken up after a night of poor sleep, glanced in the mirror and thought, “I look tired?”

You’re not imagining it.

I am a neurologist who specializes in sleep medicine. And though “beauty sleep” may sound like a fairy tale, a growing body of research confirms that sleep directly shapes how our skin looks, how youthful it appears and even how attractive others perceive us to be.

What happens during sleep

Sleep is not just down time. Your body moves through distinct stages that serve different restorative functions. Deep, slow-wave sleep is the primary stage during which the body prioritizes tissue repair, muscle recovery and collagen production.

Growth hormone is released during this sleep stage, with most daily secretion occurring in the early part of the night. This hormone drives the body’s repair and rebuilding processes, helping to heal tissues, restore muscles and boost the production of collagen, the protein that keeps skin firm and elastic.

Slow-wave sleep also creates a unique hormonal environment that benefits the skin. Cortisol, the body’s main stress hormone, falls to its lowest point during this stage. Lower cortisol protects collagen, reduces inflammation and supports the skin barrier. At the same time, higher levels of growth hormone and prolactin, a hormone that helps regulate the immune system and cell growth, enhance immune function and tissue repair, helping skin recover from daily stressors.

The skin–sleep connection

The skin is your body’s largest organ, and it works hard while you sleep. Adequate sleep promotes hydration and barrier function, helping your skin maintain moisture and resist irritation. In contrast, sleep deprivation increases water loss through the skin, leaving it drier and more vulnerable to damage and visible signs of aging.

Sleep also plays a role in acne, a common skin condition that affects people of all ages. Poor sleep can raise inflammation and stress hormones such as cortisol, both of which may worsen breakouts. Consistent, restorative sleep, on the other hand, supports your skin’s ability to regulate oil production and recover from irritation.

Collagen repair and elasticity also depend heavily on adequate rest. In one study, short-term sleep restriction, defined as just three hours of sleep per night for two nights in a row, reduced skin elasticity and made wrinkles more noticeable.

Chronic sleep deficiency, also known in sleep medicine as insufficient sleep syndrome, refers to getting fewer than seven hours of sleep per night for at least three months, accompanied by daytime fatigue or impaired functioning. This state disrupts collagen production, weakens the skin barrier and fuels low-grade inflammation that undermines healing.

Studies show that the hormonal disruptions that occur with sleep loss elevate cortisol and accelerate oxidative stress, an imbalance between cell-damaging molecules and the body’s defenses, while impairing the very processes that keep skin resilient. Over time, these changes accelerate biological aging and leave the body less resilient to daily stressors.

Your face tells the story

Sleep loss does not only affect how skin functions. It also changes how the face appears to others. Controlled studies show that even after a few nights of reduced sleep, others consistently rated them as less attractive, less healthy and more fatigued. Common cues include paler skin, darker under-eye circles, red or swollen eyes, drooping eyelids and downturned mouth corners.

These signals are subtle but socially significant. Observers are less inclined to interact with or approach someone who looks sleep-deprived. Sleep also affects empathy and aesthetic perception, meaning that people who are well rested not only view others more positively but are also, in turn, viewed more positively by others. This reciprocal effect may help explain why job interviewers, dates, or even friends tend to respond more favorably to a well-rested face.

Sleep even influences how we perceive ourselves. People with poor sleep often report lower satisfaction with their own appearance.

Supporting your health

Prioritizing sleep is a powerful and accessible way to support appearance and overall health. So the next time you consider trading sleep for a few extra hours of work or entertainment, remember that your skin, your health and even your social presence will benefit from those hours of rest.

Joanna Fong-Isariyawongse does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.