When you’re sleepy, you’re tired or drowsy. Snow White’s dwarf who is always yawning? That’s Sleepy!
Sleepy people need to sleep. Sleepy things (like a sleepy yawn or a sleepy face) can be evidence of how exhausted someone is. If a place is described as sleepy, it means “unexciting” or “without activity,” so you could call the little village where your grandparents live a sleepy town. You can also call your tired friend a “sleepy head,” a term that’s been around since the 1500s.