Ooor... maybe we are supposed to have a diurnal rhythm slump at midday/afternoon. Short-circuiting that with a sugar—>insulin hit or a caffeine wallop creates all manner of consequences with which we struggle in the western world.
Don't get me wrong, I'm all for tasty snacks, and a lot of them. Seriously, watching me eat is a spectacle. I can put away 5000+ calories in one sitting. But just putting something in your pie hole because you're bored or tired, that creates more problems than it solves. Go for a walk or take a nap.