I understand, my sister is bipolar, meds are a necessity. Call his doctor and let him or her know the situation and how bad it is.
And try giving him lean meat, healthy carbs, and fruit for breakfast, and in his lunch. Low fat cottage cheese, whole wheat toast or crackers, a small handful of nuts, grapes, yogurt, an apple with peanut butter, a lean meat (turkey or ham made from turkey) sandwich on whole wheat bread or pita with low fat cheese are all good choices. (Turkey has a bad rap for putting us to sleep but researchers believe it's the foods we eat with it.)
If he can eat at least some of these foods every 3 hours (a mid morning snack would help) his body will be constantly digesting and delivering a steady stream of sugar into his bloodstream, which should help keep him alert. Candy, soda and other sugary foods aren't good choices as they will give him an initial "boost" but then he'd have the inevitable sugar crash.