I do it by being a lazy sack of shit . In all seriousness though, you can perform at a much higher mental caliber if you get the necessary sleep. It more than makes up for the lost time.
7am wake up, get ready, eat
9am 30 minute cycling commute to work (exercise too!)
9:30-5:30 work (this one’s tricky, you can get everything done in an 8 hours or less if you avoid distractions and take a half-hour lunch)
6-11 cook, eat, enjoy my life and be social
There seem to be two traps that people fall into: (1) being too social and distracted during work and making up for it by staying there for 10-18 hours—grad school is work not your life, (2) not planning/scheduling well enough to know where to cut corners, not optimizing experiments so they take less time, and reading entire papers instead of focusing on abstracts/captions/conclusions—basically, not being efficient. I guess the take-away message is to be focused and efficient.
The other thing to realize is that work hours is only weakly proportional to the time it takes to graduate. Pick your research problems/experiments carefully and get the biggest academic bang for your buck.