Every article on the internet says that bananas are excellent for energy. 2 bananas can help sustain energy levels for 90 minutes of rigorous exercise. Tryptophan is mentioned as an essential amino acid that boosts seratonin levels (happy feeling, sometimes a sleepy feeling). As opposed to other foods that contain tryptophan, bananas are at the bottom of the list on the amount of tryptophan in them. I see no reason to not eat bananas for energy. I have yet to have eaten a banana that has made me feel sleepy. Now maybe if I ate some turkey preworkout it would be a different story. Turkey has pretty high levels of tryptophan in it.