Autochthonous intestinal bacteria and coprophagy: A possible contribution to the ontogeny and rhythmicity of Slow Wave Sleep in mammals

A sleep-inducing substance Factor S (FS) has been identified as a member of the muramyl peptide family of molecules which constitute the cell wall of bacteria. FS-like substances are unable to be synthesized by mammals suggesting that the symbiotic bacteria of the gastrointestinal tract are a prime source of FS. The present paper considers the relationship between the ontogenesis of Slow Wave Sleep (SWS) and the colonization of the intestine with strictly anaerobic bacteria. The practice of coprophagy in rats and rabbits is considered as an efficient method of FS ingestion during the sleep period.