Why do I get tired after a big meal?
10-01-2013
We have all had that feeling after a big meal where we need to go and have a lie down. No wonder so many countries have siestas after their lunch. When you think about it though it seems a bit strange as calories, which make up a large part of the food that we eat, are supposed to give us energy so why do we feel tired after eating?
The reason that we feel tired is that generally when we eat a big meal it is also one that is full of high-fat, high-carbohydrate and high-sugar foods, say like Christmas lunch. These actually trigger a neural response as soon as they hit the small intestine.
This response, in what is referred to as the parasympathetic nervous system, sends a message that tells our body to slow down and to expend energy on digesting the food rather than go out and seek more food.
At the micro-biological level, there is a group of brain cells called orexin neurons that are found in the hypothalamus. They are extremely sensitive to glucose levels, which spike after a big meal. Those neurons produce a protein, orexin, which moderate the wakefulness of the brain.
After a big meal we are pretty much shut down by our brain so we can digest it.
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