Effects of Delta-Sleep-Inducing Peptide on 24-Hour Sleep-Wake Behaviour in Severe Chronic Insomnia

This pioneering clinical study, published in European Neurology, evaluated the effects of DSIP (Delta-Sleep-Inducing Peptide) in 14 patients with severe chronic insomnia who did not respond adequately to conventional treatments. The trial used a double-blind, placebo-controlled design, with intravenous DSIP administration over 7 consecutive nights.

DSIP is a nonapeptide (Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu) originally isolated from rabbit blood during slow-wave sleep in 1977. Unlike conventional hypnotics (benzodiazepines and barbiturates), DSIP is not a direct sedative but acts as a neuroendocrine modulator of the sleep-wake cycle, interacting with serotonergic, GABAergic, and opioidergic systems.

Results demonstrated substantial improvement in nocturnal sleep from the first dose, with progressive increase in sleep efficiency throughout treatment. Notably, by the end of the 7 nights, sleep efficiency of treated patients reached levels comparable to normal controls — an extraordinary result considering the severity and chronicity of these patients' insomnia. Polysomnography confirmed increased slow-wave sleep (N3 stage) and reduced sleep onset latency.

A particularly interesting aspect was the absence of significant side effects and the maintenance of benefits for a period after treatment discontinuation, suggesting that DSIP promotes a "reset" of sleep patterns rather than simply inducing sedation. There were no reports of dependence, tolerance, or rebound insomnia — common problems with conventional hypnotics. Although DSIP did not advance to widespread clinical use due to the requirement for intravenous administration, this study remains an important reference in sleep neurobiology.