If you feel sleepy after eating, particularly after sweets or bakery products, you are normal. Eating sugary foods causes your brain to make large amounts of the neurotransmitter, serotonin, that makes people fall asleep naturally at night.
Eating sugary foods or those made from flour, such as bakery products or pastas, causes blood sugar to rise higher than normal. This causes your pancreas to release large amounts of insulin, which drives one of the protein building blocks called tryptophan from your bloodstream into your brain, where it is converted to serotonin that makes you feel sleepy.
Many people can avoid feeling sleepy after eating by restricting foods that are high in sugar and flour. When it is important for you to be alert, eat foods that do not cause a high rise in blood sugar, such as vegetable salads, nuts, seeds, fish or chicken.