However you define productivity, I still work the same number of hours in a given day, so whether it's more output or better output, it's still all the same to me. There's no reason for me to invest the extra hours in sleep to improve it when I can invest that time in things I enjoy. I don't see how that changes anything I said. My work is defined by hours, not goals, not lines of code, but hours.

You can negotiate a shorter workweek and then get extra time. And that's easier if you're productive.

I've done it, and others have as well.