Right. It can't possibly have anything to do with discipline.
Certainly folks at the bottom of the economic ladder are sleep deprived due to needing to work multiple jobs and take care of kids. But there are a lot of high-status communities that put a positive value on sleep deprivation. I hear from multiple sources that this is true in medicine. I know from experience that this is true at MIT.
Those cultures need to change. There is no good reason for an introductory computer architecture class to make its assignments due at 6am.
"It needs to be turned in by the earliest time I might feel like starting work in the morning."
You're absolutely right though. It would be more sensible to have the cronjob run at Sunday 8pm instead, given that nobody is in the office until Monday morning anyway.