Why do we feel sleepy after eating meal?

[askhan]

It is usually observed after taking good meal we start feeling sleepy; why is it so?

[JackBean]

you mean after taking heavy/oily/fleshy/unhealthy meal It's because such food is hard to digest so the body need to concentrate on the digestion, that is redirect the blood flow to gut and intestine, produce lots of juices, enzymes etc.

[askhan]

so sugar or blood glucose levels have something to do with sleep?

[animus]

The above replies may be right too, but my teacher told us that it's because since the proteins in food are composed of a chain of amino acids—one of the varieties being tryptophan—tryptophan is either a part of, a precursor of, or helps to make (I'm not sure, exactly) serotonin, which is a neurotransmitter involved in sleep. I would assume it is an inhibitory neurotransmitter.

Okay, I looked it up. WebMD says: "L-tryptophan is an essential amino acid. The body can't make it, so diet must supply tryptophan. Amino acids are building blocks of proteins. Foods rich in tryptophan include, you guessed it, turkey. Tryptophan is also found in other poultry, meat, cheese, yogurt, fish, and eggs.

Tryptophan is used by the body to make niacin, a B vitamin that is important for digestion, skin and nerves, and serotonin. Serotonin is a brain chemical that plays a large role in mood and can help to create a feeling of well-being and relaxation. "When levels of serotonin are high, you're in a better mood, sleep better, and have a higher pain tolerance," says Elizabeth Somer, MA, RD, author of numerous nutrition books, including her latest, Eat Your Way to Happiness.

Tryptophan is needed for the body to produce serotonin. Serotonin is used to make melatonin, a hormone that helps to control your sleep and wake cycles."

And so they go on for another page saying the same thing. Article here.

[JackBean]

Interesting idea.

[animus]

Waking this thread up; sorry..

But recently on Mythbusters they tested this myth; Do we feel sleepy after Thanksgiving dinner because of the high amounts of tryptophan in turkey?

In short, no. They had two guys on the team eat different meals: a big dinner including turkey, a big dinner without the turkey but a protein-rich equivalent, straight-up tryptophan pills, and a regular-sized meal. They tested tiredness through points scored on "Whack-a-Mythbuster" (ha ha) and it turned out that the huge meals made them tired and score much less, while neither the tryptophan nor the small meal did anything. The small meal scores even beat the control.

Interesting! I wonder what's up with the contradiction. Hm. I don't know what conclusion to draw about all this—just figured I'd put it out there.