ABSTRACT
The somnogenic effects of viable microorganisms, killed or non-replicating microbes, and isolated microbial components appear to be related to their ability to initiate an immune response and to trigger the production and release of endogenous immune modulators that promote sleep. Data collected in infectious disease models suggest that immune processes contribute to microbially induced sleep enhancement and that alteration of the immune response capabilities of the host modifies the magnitude and temporal pattern of the sleep responses elicited by microbial challenge. Little information is available regarding the clinical relevance of altered arousal during microbial infections. However, the occurrence of prolonged periods of increased sleep during various infectious states in animals and humans implies an adaptive function for infection-induced sleep. Infection-induced increases in sleep propensity may therefore promote the animal’s remaining in comparatively secure surroundings while physically debilitated, thereby potentially reducing the possibility of predation or injury during illness.
