Actually, this seems like a theory he thought up one night while he couldnt seem to sleep from eating too late.
from what I have read and what seems like common sense is to not eat in evening, Night time is when we regenerate, that is where all the energy is spent, not digesting food, if you are digesting food while you are asleep then you do not get regenerated as much
Sleep is a very active process, to think that the body is so at ease during sleep that it can deal with foods more efficiently is foolish.
During sleep many body regeneration functions are carried out, and you do not want your body to be dealing with food while this is happening.
Digesting food is a day time event, and peak digestive enzyme secretion is at mid-day.