DSIP (Delta Sleep-Inducing Peptide): Research Overview

What is DSIP?

DSIP is a nonapeptide, a chain of nine amino acids (Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu), with a molecular weight of about 849 Da.^{[1], [9], [10]}

It was described in 1977 by Schoenenberger and Monnier after isolation from rabbit brain blood. Since then more than a thousand papers have examined DSIP, but the gene, precursor protein and receptor for DSIP itself have not been identified.

See also: DSIP sequence and molecular data

What does DSIP stand for?

DSIP stands for Delta Sleep-Inducing Peptide.^[1]

"Delta" refers to delta-wave (slow-wave) activity on the electroencephalogram (EEG), which the original rabbit experiments reported was enhanced after infusion of the synthetic peptide.

Does the name "Delta Sleep-Inducing Peptide" prove it induces sleep?

No. The name records an early experimental observation and is not evidence of clinical efficacy.^[9]

A 2006 review concluded that the hypothesis of DSIP as a sleep factor is "extremely poorly documented and still weak", noting that the link between DSIP and sleep was never fully characterized.

How was DSIP discovered?

DSIP was isolated in 1977 by the Schoenenberger-Monnier group in Basel from the cerebral venous blood of rabbits under low-frequency electrical stimulation of the thalamus.^{[1], [9]}

Synthetic versions were then infused into the brain ventricles of rabbits under double-blind conditions, and only DSIP showed significant enhancement of delta and spindle EEG patterns among the compounds tested.

See also: DSIP research history

What mechanisms have been proposed?

No established mechanism exists. Proposed roles involve neuroendocrine signaling, but DSIP's natural biological activity "still remains obscure".^[9]

DSIP-like immunoreactivity has been reported in hypothalamic and pituitary tissue, the gut and other sites, which has led to broader hypotheses than sleep alone.

See also: DSIP mechanism: what is and is not known

Has DSIP been studied in humans?

Yes. Small clinical studies between 1981 and 1992 gave DSIP to people with insomnia, with mixed results.^{[3], [7], [8]}

Some early studies reported improved sleep measures, while a later double-blind study concluded that short-term DSIP treatment was not likely to be of major therapeutic benefit. The studies are small and old.

See also: DSIP human research · DSIP studies database

Is the DSIP evidence conclusive?

No. Findings are inconsistent across studies, human trials were small, and DSIP breaks down quickly after administration.^{[9], [8]}

Reviewers have noted that certain synthetic DSIP analogues, but not DSIP itself, showed significant slow-wave sleep promotion in rabbits and rats, and that DSIP is degraded rapidly after outside administration.

How is DSIP identified analytically?

Identity is typically checked by mass spectrometry and purity by HPLC; the two answer different questions.

See also: DSIP analytical testing explained