Chronic intracerebroventricular infusion of insulin causes selective increase of slow wave sleep in rats

Sleep patterns were continuously recorded in rats receiving chronic intracerebroventricular (i.c.v.) infusions of insulin. The i.c.v. administration of insulin resulted in a selective increase (25%) of the daily duration of slow wave sleep (SWS), whereas the duration of paradoxical sleep (PS) remained unchanged. The neutralization of peripheraland/or central insulin by means of continuous intravenous or i.c.v. infusions of anti-insulin serum brought about a selective decrease of SWS, whereas PS remained unchanged. The present findings are discussed with regard to the present knowledge of the origin and the role of brain insulin.