Increased sleep following intracerebroventricular injection of the delta sleep-inducing peptide in rats.

Synthetic delta sleep-inducing peptide (DSIP) was injected intracerebroventricularly into rats in a dose of 7 nmol/kg. A significant, 20% increase in total slow wave sleep (and total sleep) was found in the DSIP-injected rats, compared to a baseline recording following a sham injection procedure. Rats injected with the Ringer solution vehicle did not change their sleep compared to their baseline recording.