Eggs Not only are eggs loaded in high-quality protein and important nutrients, but those breakfast favourites are a natural source of tryptophan, an amino acid that plays a role in creating serotonin, a chemical that helps regulate sleep cycles. Although the results are based on adult subjects, data published in British Journal of Nutrition suggests improvements in sleep after 19 days of tryptophan-rich egg-white protein hydrolysate was consumed versus those who did not eat the egg whites. Image Source: Unsplash / Jakub Kapusnak