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Terminus Peptides
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Research profile · Peptide

DSIP

Also known as Delta sleep-inducing peptide, Emideltide

Early human — evidence level 3 of 4: Early human evidenceExperimental — UK regulatory status: Experimental — not authorised for human use in the UK

Overview

A nonapeptide isolated in 1977 and proposed as a sleep factor, whose status as a discrete endogenous signalling peptide has never been confirmed.

Category
Peptide
Highest evidence level identified
Early human evidence
Last scientifically reviewed
20 August 2026
Last regulatory review
20 August 2026

Mechanism under investigation

DSIP is a nonapeptide isolated in 1977 from the cerebral venous blood of rabbits and initially proposed as a sleep-promoting factor. Its mechanism has never been established: no gene, no precursor protein and no receptor has been identified, so there is no confirmed pathway by which it would act. Proposed effects have ranged across sleep regulation, circadian rhythm, stress response and pain modulation, but these remain hypotheses generated by administration studies rather than conclusions drawn from a mapped mechanism.

Research areas

  • Sleep research
  • Neuropeptide biology

These are fields in which the compound has been investigated. Listing a field is not a statement that anything was demonstrated within it.

Current evidence

In-vitro evidence

Cells, tissues or biochemical systems outside a living organism.

Limited and largely historical. Conformational and blood-brain-barrier transport work exists from the 1980s and 1990s. There is no receptor pharmacology, because no receptor has been identified.

Animal evidence

Studies in living non-human animals.

Present and historical. Early work reported increased slow-wave sleep after central administration in rats and electroencephalographic changes in rabbits. Recent animal work is sparse and indirect: the most recent notable study tested a fusion construct rather than the peptide itself, and found the fusion more effective than the base peptide.

Human observational evidence

Studies observing people without assigning an intervention.

Thin. Diurnal-rhythm plasma studies of DSIP-like immunoreactivity exist, but they measure immunoreactive material whose identity is exactly what is in question.

Clinical-trial evidence

Studies assigning an intervention to human participants.

A small, old and largely negative human literature, with no registered trials anywhere. The pattern is consistent: the smaller and less controlled the study, the more positive the result. An open, uncontrolled study in seven patients reported sleep normalised in six. The two properly controlled studies in chronic insomnia were negative — one found no significant difference against baseline or placebo and concluded any improvement was of little clinical significance, and the other described its statistically significant effects as weak, partly attributable to changes in the placebo group, with no improvement in subjective sleep quality.

Study limitations

  • The fundamental limitation: no gene, precursor protein or receptor has ever been isolated, so there is no confirmed mechanism and no way to verify that administered peptide acts on a genuine endogenous system. A 2006 review in the Journal of Neurochemistry called it a still-unresolved riddle, and it remains unresolved.
  • The entire controlled human literature comprises a handful of studies from 1981 to 1992 with sample sizes of roughly six to sixteen, conducted before trial registration or modern reporting standards.
  • Results are inconsistent and inversely related to methodological rigour. The open, uncontrolled study was strongly positive; both properly controlled studies in chronic insomnia were negative.
  • No registered trials exist, and no modern human research. The field has been effectively dormant for over thirty years, with recent activity confined to animal work on modified fusion constructs.
  • Endogenous DSIP-like material is reported to be rapidly degraded, raising an unresolved question about how administered peptide could produce durable central effects.

UK regulatory context

Experimental — not authorised for human use in the UK

A compound appearing in research literature that holds no UK authorisation for human use in any indication.

Source: The Human Medicines Regulations 2012, regulation 46 — prohibition on sale or supply of an unauthorised medicinal product (opens legislation.gov.uk in a new tab) (legislation.gov.uk)

Regulatory classification is jurisdiction-specific. A compound authorised elsewhere is not thereby authorised in the UK, and a supplier’s description of a substance does not determine how it is classified in law. See safety and regulation for the framework and the authoritative sources.

Safety and interpretation

The small human studies from the 1980s reported good tolerability, with one explicitly recording no psychological, physiological or biochemical side effects. With total controlled human exposure amounting to a few dozen people across four decades-old studies, that constitutes an absence of detected harm rather than a demonstration of safety. No modern safety data, no pharmacovigilance and no registered trials exist.

References