hi tofumanic!
I'm not sure if this is the sort of answer that you're looking for, but I'll add my two cents.
I've recently been in your position. I'm around your age and I just finished grad school. I'd also gone through days where I absolutely could not wake up. I slept through alarms, the phone, etc.
I've found that since I've completely eliminated all caffeine and refined sugar from my diet and made a point of not eating anything at least 4 hours before I go to bed, this situation has improved *tremendously.*
I still study late and go to bed at 4-5 am, but I make sure not to snack after midnight. Quitting caffeine was much more difficult than cutting out all sugar, but it has also vastly improved my quality of sleep. I don't actually get any more hours of sleep than before, but I no longer need "hibernation" days!
I hope that this helps.
Best wishes,
Noele