Re-wind: The loud history of the alarm clock

We don't think of them as a luxury exactly, those few extra moments of sleep after one hits snooze on an alarm. But that's really what they are.

- Nikhil Narayanan

Through most of history, it was impossible to set a personalized wake-up call, unless one were royalty or nobility.

Before we get to how alarms have worked, through the centuries, have you ever wondered why the default snooze duration is nine minutes? Do you secretly think it's because the phone manufacturer is trying to help you cheat, and knows 10 would simply be too much?

It isn't that; well, not exactly.

Long before smartphones, the snooze feature existed in mechanical timepieces. Because of the way their gears were designed, it was nearly impossible to allow exactly 10 minutes of extra sleep before the alarm went off again. What clockmakers could manage was either a little over ten minutes, or a little under.

They chose the latter, rightly assuming that 11 would be pushing things too far. And so the nine-minute snooze was set. Digital clocks, and then smartphones, preserved this pattern. It was, by this time, habit and tradition. Today, it lives on still.

Meanwhile the alarm, in some form, has been around for millennia. Clocks—not mechanical or electronic, but water-based, star-based, shadow-based—have marked the hours for thousands of years. But the idea of a sound-based wake-up system? That's where it gets interesting.