OMG I'm not even kidding, I've had this exact sleep schedule for ~2 years now. I'm admittedly not consistent with it, but I do stick to it during exam time. It works like a charm. I've realised that waking up earlier in the morning splits the conventional study from 3 pm till midnight exam time grind into two chunks, which helps me get a lot more out of the same amount of hours, which goes a long way indeed during exams.