Chapter 8: The Divine Office at night 

It seems reasonable that during wintertime, that is from the first of November until Easter all should arise at the eighth hour of the night. By that time, having rested until a little after midnight, they may rise with their food well digested.

(From Ch. 8 of Saint Benedict's Rule, trans. by Patrick Barry OSB, 1997.)

I think good digestion concern Benedict, not just because he's solicitous for others' comfort, but because of his firm grasp that the body participates in the prayer of being.