Interferon alpha-2 enhances slow-wave sleep in rabbits.

Interferon alpha-2 (IFN) is a leukocyte product with several biological properties including antiviral activity, pyrogenicity and enhancement of immune functions. We report here that an additional facet of IFN activity is its ability to enhance slow-wave sleep (SWS) without greatly altering other aspects of sleep. Intravenous or cerebral intraventricular injections of human IFN into rabbits induced enhancement of SWS, electroencephalographic slow-wave (0.5-4 Hz) activity and brain temperatures. IFN induced slight reductions in rapid-eye movement sleep. Animal behavior, brain temperature changes that occur during the transition from one arousal state to another, and the cyclic nature of states of vigilance remained undisturbed after IFN treatment. The sleep-promoting activity of IFN may be related to feelings of lassitude and sleepiness that often accompany viral disease and interferon therapy. That IFN and other immunoactive substances, e.g. interleukin-1 and muramyl peptides, can enhance sleep suggests that sleep is linked into the immune response.