I've seen that suggested a few times before; a related suggestion that I found more compelling was related to a particular old-style alarm clock. At the time it was set for the clock would make a small click, then a few seconds later, a loud buzz. The owner of the clock could tell how well-rested he was by whether the click or the buzz woke him up.
I don't think your division quite divides reality at the joints- I can get up to an alarm even if my day will be ruined by lack of sleep, but I generally will sleep long periods if I don't have an alarm set. (If by 'oversleep' you mean 'not take alarms seriously,' then why argue that group 2 must use them, when they don't use them well?)
This is the public group instrumental rationality diary for Christmas week. It's a place to record and chat about it if you have done, or are actively doing, things like:
Or anything else interesting which you want to share, so that other people can think about it, and perhaps be inspired to take action themselves. Try to include enough details so that everyone can use each other's experiences to learn about what tends to work out, and what doesn't tend to work out.
Thanks to everyone who contributes, and I hope everyone is having a nice holiday!
Previous diary; archive of prior diaries.