I also find my sleep schedule to be flexible (although I'd be wary of your assumption that this is true for everyone.) I find that the key ingredient is others

I also find my sleep schedule to be flexible (although I'd be wary of your assumption that this is true for everyone.) I find that the key ingredient is others' expectations. If I'm going to be arriving at a workplace with the person I report to sitting right opposite me, and sleeping in means arriving an hour or more after them, then I can get in gear, avoid pressing snooze, and catch the 07:33. At my previous job, the norm was to arrive between 10 and 11: I was rarely up more than 15 minutes before my carpool arrived, and the idea of getting up earlier regularly gave me headaches. Edit: some stuff I've done for a while: no caffeine after 18:00, no blue light after 21:00. Falling asleep is much harder if I don't do these things.