When you get up in the morning, take a moment to curse the ancient Greeks. One of them, Plato, invented the thing that torments you. Learn the story of the earliest alarm clocks.
Despite their love of logical rigor, people weren't always exact in the ancient world. Without easy access to precise time-keeping, it was difficult to be exact. But even back then, some people weren't fans of waiting around for a crowd to show up, and Plato was one of those people. He needed to find a way to get himself, and his students, up at a certain time. And so he invented one.
Possibly the oldest clocks in history are water clocks. Water drips from one vessel into another via a small hole. As long as that hole stays the same size, and the vessels stay the same size, the clock counts down for a set amount of time. But it doesn't wake people up. Plato had to add some bells and whistles. He ended up adding only the whistles. He added a tube to the filling vessel. It formed a siphon. When the water got high enough to fill the tube and start spilling over, all of it at once was siphoned off into yet another vessel. This last vessel was mostly enclosed, but it had thin openings, making it whistle like a tea kettle when it filled up quickly. That woke people up, and got them to their lectures on time.
There have been quite a few other low-tech alarm clocks since then. One filled a vessel until it became so heavy it dropped, activating a catapult that chucked a rock into a metal plate. One was a candle with a ball embedded in it. When it burned down, the ball was released, and fell onto a metal surface. If only they had a second ball, embedded in the wax slightly below the first ball. It could have made for the first snooze alarm in history.