In a study on adult male rats, giving a single injection of delta sleep‑inducing peptide (DSIP) at 1 mg per kilogram boosted the brain waves associated with deep sleep (delta and theta) for many hours after the dose. The peptide made these low‑frequency waves more frequent and stronger, suggesting it could help promote deeper, more restorative sleep.

The effects of delta sleep-inducing peptide (DSIP) on the EEG and power spectra of adult male Wistar rats (b.w. 180-220 g) were studied by power spectra analyses of EEG wave forms recorded continuously for 12 h after DSIP administration. The animals were given DSIP i.p. (1 mg/kg). Saline-injected rats served as the corresponding control. Recorded bursts of high amplitude EEG in the 1-9 Hz range (delta and theta) were found to be more frequent in DSIP-treated animals, while power spectra and (delta) wave activity were enhanced in comparison with the control and a statistically significant increase was registered in all experimental points after DSIP (2 h P < 0.05; 4 h P < 0.05; 5 h P < 0.05; 6 h P < 0.05; 7 h P < 0.01; 11 h P < 0.05). In addition, DSIP significantly elevated both the EEG output in the (delta) range and sleep activity. These results suggest that DSIP should be considered as a potential agent for the treatment of sleep disturbances in human medicine.