A review of recent studies relating ligand diffusion, general anesthesia, and sleep.

This review article presents 3 theories related to ligand diffusion, general anesthesia and sleep. The first theory describes the diffusion of molecules across a protein surface to a receptor. It is based on the effect of the amino acid side chains on the protein surface on the structure of bulk water nearby. This influence creates pathways, called chreodes, through the water near the protein surface, permitting a rapid diffusion of molecules to the receptors. A second theory involving the role of chreodes presents a mechanism of action of nonspecific anesthetic agents. These agents interrupt the diffusion of neurotransmitter molecules to their receptors, bringing on the anesthetic effects. Finally, building on the similarities of anesthesia and sleep, a theory is presented proposing that an external agent influences sleep in a way similar to that of the nonspecific anesthetic molecules. This external agent is proposed to be elemental nitrogen. Several observations are presented to support this mechanism.