So, hopefully 'per day' is better explained in the PH. As it is, I'm wondering where the line is supposed to be drawn. If you 'extended rest' at 10 pm, is that your rest for yesterday, when you started, or today when you ended? And of course, as a definition it still has the wonderful loophole that the 3e resting rules did- if you're on a plane with a different 'day-cycle', what happens? If you're on the plane of Forever Night, where a 'day' is a million years, or the plane of Speedy Passage, where a 'day' is 5 minutes, does the game collapse in on itself?