You’re sweaty in sleep. Sweat is the body’s way of cleaning itself and cooling down. It can also help you stay cool if it evaporates quickly enough, but that depends on where you are and what other factors are present (such as air conditioning or your clothes).
What causes sweating?
Sweating for no reason (no stress, no exercise) happens because something has triggered an increase in your sweat glands’ activity. This could be due to stress, exercising too much or not drinking enough water; all these things cause the body to make more heat than usual. The heat isn’t dangerous unless it gets out of control! If there’s too much heat building up inside your body, then some important organs like the heart may suffer damage over time – this is called hyperthermia (too much thermoregulation).