What has a bed but never sleeps?

The answer to this riddle lies in the descriptive language we use for natural features. A river has a "bed," which refers to the ground or channel over which its water flows. This term has been used since at least the late 1700s to describe the bottom of a river. Just as a human bed provides a place to rest, a riverbed is the foundational surface that contains the moving water.

Rivers are always in motion, constantly flowing downhill due to gravity, which is why they "never sleep." From their source, often in mountains, they gather water from precipitation, melting snow, and groundwater, carving out valleys and shaping the landscape as they journey towards a larger body of water like an ocean or lake. Even when the flow appears calm, the water is continuously moving, carrying sediment and transforming the environment around it.

These dynamic waterways are vital to life on Earth. They sustain countless ecosystems, provide fresh drinking water for humans and animals, and have been crucial for transportation and agriculture throughout history. Rivers are powerful geological forces, capable of eroding rock to form canyons and depositing material to create fertile floodplains and deltas. The continuous flow of a river, even through bends and meanders, highlights its ceaseless activity, making the riddle a perfect description of this essential natural phenomenon.