It has everything to do with cortisol. As you may know, collagen, hyaluronic acid, and lipids tend to suffer when your cortisol levels are increased. These other processes are pushed into the background so that your body can focus all of its energy on this "fight or flight" response. As these three components decrease over time, "skin thinning" can occur, which can actually make the skin thinner and less elastic. As a result, your skin barrier weakens, which can lead to some concerns – think of irritation, dryness, and premature aging.
So where does sleep come in? Well, says Bowe, sleep and stress are deeply intertwined. "When the quality or quantity of your sleep is compromised, especially over time and especially if it's more than one night, it is registered as stress by the body and brain," she says. This relationship between sleep and stress is supported by research, as one study found that short periods of sleep were associated with perceived stress in working adults. Similarly, previous research found that those participants who were limited to just 4.5 hours of sleep a night for a week felt more stressed, angry, sadder, and mentally exhausted.
In addition, your skin goes into "recovery mode" at night: During the nightly sleep cycle, the HGH (human growth hormone) increases sharply, which helps to rebuild the body tissue and stimulate cell production to replace cells that were damaged during the entire sleep cycle. If you don't get enough sleep, your skin cells won't regenerate as much during this recovery process. And so, damaged cells form, which can make your skin look dull, dry, and clogged.