"Carbs which quickly raise blood sugar (those with a high glycemic index) may hasten sleep, especially when eaten four hours before bedtime, the researchers report. Such carbs may boost tryptophan and serotonin, two brain chemicals involved in sleep, the study suggests"

https://www.webmd.com/sleep-disorders/news/20070214/carbs-may-help-you-fall-asleep-faster#:~:text=Carbs%20which%20quickly%20raise%20blood,in%20sleep%2C%20the%20study%20suggests.