When healthy sleepers ate carbohydrate-rich suppers of veggies and tomato sauce over rice, they fell asleep significantly faster at bedtime if the meal included high-glycemic-index (GI) jasmine rice rather than lower-GI long-grain rice, in a study published in the American Journal of Clinical Nutrition. While the authors aren’t sure how it happened, they speculated that the greater amounts of insulin triggered by the high-GI meals increased the ratio of sleep-inducing tryptophan relative to other amino acids in the blood, allowing proportionately more to get into the brain.