Every year at Thanksgiving, many of us stuff ourselves with turkey, gravy, and pumpkin pie (with whipped cream on top). You may have heard that eating turkey makes you feel sleepy. This myth stems from the fact that turkey contains the amino acid tryptophan, which gets converted into the well-known sleep-inducing hormones serotonin and melatonin. However, contrary to popular belief, turkey is not that high in tryptophan, at least not any more than any other meal you may eat. Yet, this often-repeated myth is well known and wide spread.
Something you might not know is that tryptophan may improve cognition. A study exploring the effects of tryptophan on cognition found that high levels of tryptophan improved memory performance (Booij et al., 2006). Participants completed a battery of cognitive tasks, which included a variant of our Double Trouble and Spatial Planning Task, after consuming a tryptophan rich supplement. The researchers found that memory performance, more specifically, recognition and speed of retrieval for short- and long-term abstract visual items, was significantly improved.
High levels of tryptophan may also improve sustained attention, which is the ability to direct and focus attention to a task over a long period of time (Luciana et al., 2007). Using a letter cancellation task to measure immediate attention and vigilance, participants were instructed to cross out all occurrences of the letters ‘E’ and ‘C’ on a piece of paper with printed capitalized letters. Following a tryptophan rich supplement, participants made fewer errors of omission on the task, suggesting that tryptophan may improve attention and vigilance.
Happy (Canadian) Thanksgiving to you and yours from all of us here at Cambridge Brain Sciences!