DSIP (Delta Sleep-Inducing Peptide)

DSIP (Delta Sleep-Inducing Peptide) is a naturally occurring nonapeptide first isolated from rabbit cerebral venous blood during electrically induced sleep in 1974, originally proposed to act as an endogenous sleep-regulatory signal. It is thought to modulate hypothalamic-pituitary signaling, attenuate stress-induced cortisol elevation, and normalize disrupted sleep architecture, though most mechanistic evidence comes from animal studies or small early human experiments. Human clinical data are limited, inconsistent, and largely from dated Soviet-era and European research with significant methodological limitations; modern placebo-controlled replication is essentially absent. Its role as a discrete endogenous sleep hormone remains scientifically debated, and exogenous DSIP's very short plasma half-life and uncertain CNS penetration raise questions about whether injectable doses reliably reproduce any physiological effect.

Evidence last reviewed: 19 Apr 2026