Many people believe that eating turkey makes them sleepy, especially after Thanksgiving dinner. However, the tryptophan in turkey is not solely responsible for this effect. Here are some key points from the search results:

• Tryptophan is an essential amino acid found in various foods, including turkey. It can influence mood and sleep as it contributes to serotonin and melatonin production.
• Eating foods with tryptophan in addition to a large number of carbohydrates leads to sleepiness. Carbohydrates come from the other typical foods at the Thanksgiving table, such as breads, potatoes, peas, corn, sugary drinks, and desserts.
• Overeating and consuming alcohol can also contribute to sleepiness during the holidays.
• Tryptophan works best on an empty stomach, so the tryptophan in turkey probably wont trigger the body to produce more serotonin. Only part of the tryptophan makes it to the brain to help produce serotonin.
• Many other foods besides turkey contain tryptophan, including cheese, chicken, egg whites, fish, milk, peanuts, pumpkin seeds, sesame seeds, soy beans, and sunflower seeds.
• The earlier darkness at this time of year and overeating in general can also contribute to feeling sleepy after a big meal.

In summary, while turkey does contain tryptophan, it is not solely responsible for making people feel sleepy after a big meal. Eating a large number of carbohydrates, overeating, and consuming alcohol can also contribute to sleepiness.