title: [Humoral sleep theories].
abstract: The common feature that characterized humoral theories of sleep is the production and accumulation of certain substances, usually end-products of metabolism, either in the tissues, in general, or in certain organs, such as the brain. When a definite concentration of such substances has been reached, the activity of the brain is depressed either directly, or through indirect influences, like vasoconstriction or asphyxia. The gradual removal of these substances during sleep leads to a return to the waking state. Humoral sleep theories were popular in the twentieth century. However, none of them lasted for a long time since either their authors or other investigators were not able to repeat them. Thus, this brief review mentions only a few of them. Today, humoral sleep theories are only of historic interest to sleep researchers and illustrate the creativity and the rich imagination of our predecessors.
authors.forename: Miodrag
authors.initials: M
authors.lastname: Radulovački
mesh_terms: D000818:Animals; D006801:Humans; D012890:Sleep / Q000502:physiology*