An object of the present invention is to provide a composition for promoting sleep, which any one can safely take on a daily basis without any risks of adverse action. In addition, an object of the present invention is to provide food and a medicament, comprising the above-mentioned composition, having an effect for promoting sleep for an individual having sleep disorders. Further, an object of the present invention is to provide a method for promoting sleep comprising administering theanine to an individual having sleep disorders, and use of theanine for preparation of the food or medicament for an individual having sleep disorders.