Slices of different kinds of bread in close up.

The Science Behind Foods That Make You Sleepy

Need to rest up for a busy morning tomorrow? According to Jo Lewin for the BBC, there are many tricks to a good night’s sleep—but, naturally, we were the most excited about his reference to food. It’s not all about fresh air, regular exercise, and a relaxing routine (which—we must note—are all very important). You should also be sure to indulge in a high-carb snack before bed. You know, one that contains something known as “tryptophan.”

“Tryptophan.” Sound familiar? It’s only everyone’s favorite “did you know…” conversation starter post-meal on Thanksgiving, right after you’ve eaten yourself silly and are about to melt into the couch; “Looks like we’ve been hit with tryptophan again. You know, that’s naturally found in turkey and it puts you to sleep,” says your uncle. Every single year.

It’s true. It does. Tryptophan is one of the eight essential amino acids, which do the heavy lifting in the body’s synthesis of protein. Tryptophan can’t be produced on its own, so we have to ingest a small amount each day. But not to worry, veg heads: it’s not found only in turkey. Tryptophan is naturally occurring in oats, bananas, dried prunes, dairy products (think warm glass of milk), tuna, chicken, bread, peanuts, and chocolate.

Another reason we’re rambling on about tryptophan?

It has a knack for producing serotonin—that gooey, lovely feeling-maker that keeps our brains and moods at their best. Even better, it can affect our melatonin levels, which are regulated by sunlight, and, when it’s dark out, the melatonin hormone is secreted to regulate our sleep patterns.

So next Thanksgiving, when the time is right and your Uncle brings up the whole “tryptophan” bit again, you have a chance to spice things up a bit with all of your new knowledge of this very resourceful nutrient.

International Journal of Tryptophan Research.

L-Tryptophan: Basic Metabolic Functions, Behavioral Research and Therapeutic Indications. Dawn M Richard, Michael A Dawes, Charles W Mathias, Ashley Acheson, Nathalie Hill-Kapturczak, Donald M Dougherty. Int J Tryptophan Res. 2009; 2: 45–60. Published online 2009 March 23. PMCID: PMC2908021