Why do we feel sleepy after eating?

Have you ever felt an unavoidable sleepy sensation after eating, especially after eating a heavy meal? Some people even doze off in their seats! Here is why this happens:

We feel sleepy or fall asleep after eating because our bodies always concentrate blood where it is needed more. After eating, our brains command both arteries and veins to expand around our stomachs and intestines. That way, these organs will be able to receive more blood with enough oxygen and nutrients to carry out the digestion of the food we have eaten. This concentration leaves some other parts of our bodies temporarily with less oxygen and nutrients, provoking the sleepy sensation (known as somnolence) we all experience now and then. This concentration is natural, and does not affect the body negatively in any way.

If you wish for other examples of our bodies concentrating more blood in certain areas to fulfil bodily functions, think about the concentration of blood in the muscles during situations of high stress (the body prepares itself for a life-or-death fight), the flush our skin acquires during sexual arousal (our bodies prepares the skin for a reproductive session), the erection of the penis (the penis gets full of blood to prepare itself for the coitus), or the loss of memory when we drink too much (the blood concentrates more blood around the liver and the kidneys, and our brains stop recording memories), just to name a few which come to my mind now.

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