Of all the modern inventions we rely on in our daily lives, the alarm clock is probably the most universally despised. Its jarring morning jangles jolt us uncomfortably out of our slumber, and back to reality. And yet however annoying alarm clocks are, they’re also indispensable in getting us out of bed. That raises an interesting question: How did people wake up before alarm clocks became so ubiquitous?
Throughout the ages, even the simple act of telling the time has presented a huge challenge to humans that we’ve tried to solve with elaborate inventions. The ancient Greeks and Egyptians developed sundials and towering obelisks that would mark the time with a shadow that moved with the sun. Dating back to around 1500 B.C., humans produced hourglasses, water clocks and oil lamps, which calibrated the passing of hours with movements of sand, water and oil.
Out of these early inventions came a few rudimentary attempts to create a morning alarm — such as candle clocks. These simplistic devices from ancient China were embedded with nails that were released as the wax melted away, leaving the nails to clatter loudly into a metal tray below at a designated time, waking the sleeper.
But such crude inventions were unpredictable and unreliable. And so, until more precise mechanical inventions were created, humans had to depend on another more innate form of timekeeping: our own internal body clocks.