DSIP (delta sleep-inducing peptide)

What it is

Not established. A 2006 review noted that no DSIP gene, precursor protein or receptor had been identified. Rat studies summarised by FDA suggest effects run partly through release of the body's own opioid peptides, without direct opioid-receptor binding.

What it is studied for

DSIP was isolated from rabbit blood in the 1970s and studied as a possible natural sleep factor. Small human studies, mostly from the 1980s and 1990s, tested it in chronic insomnia; a single case report covered narcolepsy, and open-label studies covered alcohol and opioid withdrawal.

What the evidence says

Small, older human trials; mixed results

A double-blind study of 16 people with chronic insomnia found only weak effects, unlikely to be of major benefit. FDA's 2026 review found the evidence insufficient for insomnia, narcolepsy or opioid withdrawal, noted headache, nausea, vertigo and low blood pressure in withdrawal studies, and flagged possible immune reactions.

How it was studied

The human studies FDA reviewed gave DSIP by intravenous injection. FDA notes that injection and nasal-spray products are marketed in the US, but no sleep trial of a spray form, or of this four-ingredient spray, was found.