nine minutes

Why does the snooze buttons go off 9 minutes later instead of some other number of minutes? James Kushton -Liberty, New York Studies have shown that it takes 10 minutes or more for someone to go back into "deep" sleep. So having it set for 9 minutes helps someone who needs it to slowly wake up. Also, back in the day when clocks were non-digital, it just so happened that the gears were set up so it could not be added as an even number: something do do with base of 12 and 60 with smart people math.  And since that is what customers expected, when digital clocks came out that is what clock makers stuck to.