The alarm clock was first introduced into the world in 1956, by General Electric. It was called the General Electric Telechron’s Snooz-Alarm. It had, of course, a 9-minute snooze interval. The original reason is purely technical: inside the clock itself, there was already a standard gear setup. Getting the teeth on the gear to line up to allow for a reasonable 10-minute cycle, was just not possible. They could either set it up for 9 minutes and a few seconds or just a little over 10 minutes.
The Science Behind 9 Minutes
So the initial reason was a technical blip! But after that, some science-backed benefits started popping up. 9 minutes is just enough for a brief rest: anything over 10 minutes allows your body to fall into a deep sleep, which will be harder to wake up from, leading to more and more pushes on the snooze button.
Hitting the snooze button once or twice is alright, but anything more than that, and you're setting yourself up for a day of fatigue. How so? Every time you snooze, your body prepares for a new sleep cycle which will be shortly interrupted. Waking up at the end of the sleep cycle is way easier than tearing your sleep cycle in the middle.
How to Change the Snooze Interval on Smartphones
On the iPhone, you simply can't. What you can do is set up multiple alarms.
On some Android-operated phones, you can head to the Clock app>tap the 3 lines icon>Settings>Alarms>Snooze Length. Or, through an existing alarm, scroll all the way down and change the snooze length from there. This way the new setting will apply only to that specific alarm.