@called4christ These are the kinds of things that
feel good to say, but aren't actually true in reality unless taken to the extremes.
Like, if you have to choose between 8 hours of sleep with no exercise, or 7 hours & exercise, 7 plus exercise is going to be better for most people. But if you are choosing between 3 hours of sleep, or 2 with exercise.... Well at that point you are so screwed it probably doesn't make a difference anyway, so get some sleep.
In my experience, this kind of advice usually comes from people who aren't very fit, or if they are fit, they don't have real life obligations holding them back, so it doesn't apply to them anyway.