Yaawwwn. According to conventional wisdom, we get sleepy after Thanksgiving dinner because of the high tryptophan content in turkey. Tryptophan is an essential amino acid that serves as a chemical precursor for serotonin, a vital neurotransmitter involved in mood and wakefulness.
Wood et al. measured social behavior using a monetary prisoner’s dilemma game in which subjects thought they were playing against other people (in fact they were playing against a computer that utilized a standardized tit-for-tat strategy against each subject). If subjects were kept on a diet low in tryptophan, they demonstrated less cooperativity in their decision making. When subjects were given a drink with high tryptophan content before playing the prisoner’s game, they were more likely to cooperate with their automated partners.
It’s exciting to think that that something as mundane as diet can significantly modulate economic decision making. Maybe it will inspire CEOs to start dosing the the water cooler with tryptophan before attempting to broker a delicate merger. However, such scenarios are not entirely analagous to the study at hand because Wood et al. deprived subjects of tryptophan prior to behavioral testing, whereas most adults are unlikely to enter an important business meeting on an empty stomach.
The title of this post is also misleading because there’s not much evidence that eating turkey increases the concentration of tryptophan in your brain. Zack Lynch of Brain Waves does a nice job of busting this myth, so I’ll just direct you there instead of re-hashing the argument.