Why do alarm clocks have 9-minute snooze instead of 10?

This is a myth. The snooze button is not always 9 minutes and never was. The first snooze alarm had a rough delay between 9 and 9 1/2 minutes.

Another early snooze alarm let one choose between 5 and 10 minutes. Modern alarm clocks include ones with a continuously variable snooze alarm length.

In 1956 at the time of the snooze button introduction, alarm clocks had standardized gears. Due to the configuration of the gears, a 10-minute snooze cycle was out of the question, so the engineers had to choose between 9 minutes or 10-plus minutes. For punctuality the engineers used with 9 minutes.

For modern digital alarm clocks: If they are to 9 minutes, the clock only needs to watch the last digit of the time. So, if you hit snooze at 5:45, the alarm goes off again when the last digit hits 4 – at 5:54. They couldn’t make a snooze period 10 minutes, or the alarm would go off right away – alternatively the clock would take more circuitry.

Although modern alarm clocks can be set to any snooze length time, attempts have been made to change the 9-minute snooze cycle but a 9-minute snooze has become the unofficial standard. Isiria.wordpress. Com/.../why-is-the-snooze-function-on-alarm-clocks-always-set-to-nine-minute-intervals.

My alarm clock lets you chose between 5, 10 or 15 minute snooze. Of course, it doesn't really matter when you hit it several times before you actually get up...

I have 2 alarm clocks, one has a 8 minute snooze and the other one 5 minutes. So it's not a general rule.

When alarm clocks were first built, the snooze gear needed to fit around the cogs that were already in the time piece. Because of the space constraints, there were basically two options: slightly over nine minutes or slightly over 10. It was believed that 10 minutes was too long and would allow a person to slip into a deeper sleep, so nine minutes became the standard.

While most digital alarms today can be programmed to have a snooze of any length, nine minutes is still the standard and default on most of them.

It seems like there is a lot of speculation out there on this topic and none of the sources seem to be well-versed in alarm clock history/technology. The answer that @borngifted gives and the answer in the article he links to (which as @albanian points out are different) do seem to be the most "logical" explanations. I like this explanation because it is a "pseudo-scientific" explanations - another favorite of mine - 9 minutes was the right amount of sleep not to go back into a "deeper" sleep.Sure.

There are all sorts of things out there that are - like the entire Fahrenheit scale - that are "pseudo-scientific". By that I mean, it's based on science, but pretty arbitrary at the same time. Sure, 0 degrees Fahrenheit is the freezing temperature of brine (salt water), by why pick brine?

Maybe someone else has the perfect answer, but if not, I'll go along with the pseudo-science.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.