What causes forced sleep after only a few bites of food?

Sleepiness post meal. This question has many facets 1-the type of food, like carbohydrades, fat, the amout of food makes a difference , the more carbohydrate , the sleepier you get 2-metabolic rate, amount of lighting, ---if you live a sedentary life, blood is diverted to digestive system, hormonal and metabolic changes produce sleepiness 3-the amount of sleep debt, if you have been behind in your sleep , you get more sleepy-.