Alarm clocks have been around since at least 245 BC, when Ctesibius of Alexandria devised a water-powered device that could “drop pebbles on a gong or blow trumpets… at pre-set times.” But it wasn’t until 1956 that the snooze button came along, allowing lazy people to stay in bed for nine minutes, then eighteen, then twenty-seven and thirty-six more minutes. Despite its short history, there are differing theories about why nine minutes has always been the standard unit of snoozing, from the very first Snooz-Alarm in 1956 all the way through to today’s default iPhone settings.
One answer, recently posted on Quora by David J. Slavik and quoted by Business Insider, suggests that nine minutes was the only practical solution for snoozing. The author, in response to a question from summer 2013, says that there was already a standardized gear system for alarm clocks when snooze buttons were invented. Because of this pre-existing setup, clockmakers had to decide whether a snooze should last nine minutes or longer than ten minutes. If you hit snooze at, let’s say, 7:15, the mechanism would know to go off again at 7:24, when the last gear turned to 4. If you’re having trouble picturing this, it might help to think about those popular clocks from the ’70s and ’80s with numerals printed on rotating cards. All four numerals moved independently of one another, so with a nine-minute snooze, the button was only connected to (and trigged by) the rightmost number.
But that’s not the only theory. It’s also been suggested that the nine-minute interval was more a marketing decision, a way to make a snooze that felt like “a few minutes” without going so long as to feel like oversleeping. Ten minutes allowed people to fall into a deep sleep, it was thought, so clock makers decided on the nine-minute gear, allowing for a shorter snooze and perhaps a happier customer.
The nine-minute delay originated with the very first snooze button, on the 1956 General Electric-Telechron Snooz-Alarm. Billed as “the world’s most humane alarm clock,” the buzzer sounded for a full forty-five minutes without interruption unless you shut it off. The clock had a round face with hour, minute, and second hands, as well as a fourth hand for the alarm setting.
Three years later, Westclox introduced its drowse alarm, featuring a switch that allowed for either a five-minute or a ten-minute snooze. Later Westclox alarms had one seven-minute “drowse” (the company didn’t change from “drowse” to “snooze” until the year 2000!). But GE/Telechron had already set the nine-minute standard, and that timing has continued to dominate for nearly sixty years.
Even though the iPhone doesn’t work with gears and real buttons, people are used to a nine-minute snooze and so Apple kept the distinctive snooze time.