What happens when a person sleeps without washing their face at night?

Dermatologists strongly advise against sleeping without washing face because dirt, sweat, makeup, sunscreen and bacteria can damage the skin barrier. It can clog pores, which cause acne, blackheads and comedones. It also inhibits the skin's process of repair and regeneration while sleeping. Not washing face before sleeping can also lead to premature aging, dryness and even potential infections.