CYTOKINES AND SLEEP

Infectious challenges induce sleep responses in the host characterized by an increase in non-rapid eye movement sleep (NREMS) followed by a period of decreased NREMS. Such sleep responses represent one facet of the acute phase response and are thus probably beneficial to the host. Certain bacterial cell wall products such as lipopolysaccharide and peptidoglycan and viral double-stranded RNA also induce sleep responses. These microbial products share the ability to enhance cytokine production. Some cytokines such as interleukin-1, tumor necrosis factor, interferon-alpha and acidic fibroblast growth factor are somnogenic. Cytokines in turn alter production of neuroendocrines and neurotransmitters, e.g., growth hormone releasing hormone and nitric oxide, which are known to be involved in sleep-wake regulation. Microbial-altered sleep thus likely involves an amplification of ongoing normal sleep regulatory mechanisms.