(1) What does he eat before and after a ride?

(2) How much sleep is he getting?

I'd suspect one or both of those. It doesn't sound to me like what he's getting on the bike is completely inadequate (depending on the sandwich of course - thickness of bread slices, sugared vs. natural PB, amount of spreads etc), but if he's starting on "E," that could be a problem.

And you read so much lately about the importance of adequate sleep, but it's still hard sometimes to go to bed when you need to, when there are so many things tempting us to stay up later.