The easiest most simple explanation is that your body will turn up the heat to slow pathogens. The more you sleep the more energy conservation your body has to fight pathogens. Your body will use different nutrients to fight the bacteria. Your body has a type of cell called leukocyte that patrol the blood being on the lookout for anything abnormal. When depleted, you need protein to help replenish. That's why chicken noodle soup is so great. It's easy on the digestion system and has protein in it. Drinking lots of water helps clear our the kidney and liver allowing you to expel the pathogens.