That is great that you found something that helps!
I believe I read that your body takes awhile to digest food and then use that food as energy. I know when my brother had an early football game on the weekend he ate a huge portion of carbs the night before. My hubby also did this when he had an early "ruck march."
I Am not sure how long the process is.. but maybe your body needed the carbs in the evening?? Do you tend not to eat after a certain time??
I'm sure there are more knowledgeable people out there that can answer this better than I can -.-