My baby suddenly screams in sleep then falls back asleep, what is it?

This behavior is called "sleep terrors" (night terrors) and is common in children 1-3 years old. Your baby isn't actually waking—he's caught between deep and light sleep, reflexively screams, and his eyes may be open but he can't see you or respond to comfort attempts. He'll spontaneously calm in a few minutes without being fully conscious; he won't remember it in the morning. This isn't a nightmare or a sign of problems; it's immaturity in sleep architecture and is usually harmless. The best response is to stay with him quietly and let it pass—don't try to wake him. If it happens multiple times a night, if daytime sleepiness is extreme, or if screaming is paired with bluish coloring or jerking, consulting a pediatric neurologist is wise. But an occasional episode every few months is just a normal part of development and resolves on its own.