Why do most alarms snooze for only nine minutes?
Most alarm clocks usually snooze for nine minutes, because when the feature was added around 1950s, the internal workings of clocks had been standardised. It was only possible to set the snooze limit around 10 minutes, however, it was believed that more than 10 minutes would allow people to fall back into 'deep' sleep. Thus, a nine-minute limit was chosen.