Published in The American Journal of Clinical Nutrition, the study claims carbs which quickly raise blood sugar (those with a high glycemic index) may hasten sleep, especially when eaten four hours before bedtime. Such carbs may boost tryptophan and serotonin, two brain chemicals involved in sleep.

People often feel drowsy after eating carbs at any time of day. If you have a hard time falling into a deep slumber each night, try staying away from the pasta-for-lunch food coma, and eat starch for dinner. Low-carb dieters, this is probably not for you.