Food >> Sleep. So...

If I packed lunch, I eat it, tell Tyrant to wake me up if anything of concern happens and then go sleepies.

If I didn't pack lunch, I consider looking around for food, realize that anything I eat would probably kill me, and then tell Tyrant to wake me up if anything of concern happens and go sleepies.

Note: Sun going down falls very much into "anything of concern", as does me suddenly shaking and/or sweating beyond what is normal, and any pokemon coming into the mausoleum. It can use it's own discretion on whether to wake me up for other situations.