Endocrinologists call it "Postprandial dip", you may call it the "mild coma" that usually occurs 2 hours after a meal. It is caused by a drop in our glucose levels and a shift in our "body clock". Our brain starts to operate slower and our body temperature starts to drop and we naturally start to feel somnolence, drowsiness and lassitude. When possible, try avoiding scheduling or attending meetings during this time frame, unless you want to start drooling during your boss’s PowerPoint presentation.