If you manage your time and life right, you shouldn't have to be sleep-deprived. Of course, that means you have to schedule your priorities, and some things won't make it as part of your life. I've gotten my Bachelor's and Master's, and I never had to pull an all-nighter beyond my first semester. I don't anticipate any all-nighters in the PhD program either.

One of the founders of the consulting firm that I worked for talked about never working past 6 or 7 PM. He never ate out, and spent that time working. You can always work more in your day without sacrificing your sleep and/or health.

At the same time, if we could all survive on less sleep, it'd be nice.