The first clinical application of carnitine is for appetite enhancement and body weight increase in diseased children in 1950s in France, Belgium, and Germany, although the used drug substance was DL-carnitine. The action of carnitine to stimulate digestive enzyme secretion was reported in animal and human and considered these action might partly explain as the reason for the appetite enhancement. Also, there were many DL-carnitine formulation for these indications in Japan in early 1960s. However, these indications for DL-carnitine disappeared in most countries. In severely handicapped patients, reduced gastrointestinal motility sometimes causes severe constipation and ileus, and there are some reports that carnitine is useful to prevent and treat these symptoms. Orexin relates to appetite, regulation of awake and sleep, and there are several article reposting that carnitine enhances abnormality of appetite and sleep.