You are stressed, sleeping badly, and a wellness post claims DSIP, the “delta sleep-inducing peptide,” lowers cortisol and calms the body’s stress system. The idea sounds tidy: one peptide for both sleep and stress. What did human studies of DSIP and stress hormones actually measure?
Three small hospital-lab studies from 1989 to 1995 looked. Two found that an intravenous infusion of DSIP lowered blood levels of ACTH, the pituitary hormone that signals the adrenal glands. None found that it lowered cortisol, the stress hormone people usually mean, and the most detailed study found no effect on either hormone at all.
Sweden and Italy: ACTH fell, cortisol did not
Bjartell and colleagues at the University of Lund gave 11 healthy men aged 25 to 39 a single intravenous injection of synthetic DSIP or saline, in random order and double-blind. ACTH-like activity in the blood dropped for at least three hours after DSIP. But plasma cortisol followed its normal daytime decline either way, and urine cortisol and monoamine breakdown products did not differ between DSIP and saline.
Five years later, Chiodera and colleagues in Parma infused DSIP over ten minutes in eight healthy young men, sometimes before a salt-water challenge or a period of standing upright. ACTH fell more after DSIP than after saline. Vasopressin, a hormone involved in water balance and the stress response, was unaffected at rest and when stimulated. Cortisol is not reported in the available abstract.
Germany, 1995: no effect when the stress system was pushed
Spath-Schwalbe and colleagues in Lubeck asked a harder question: does DSIP blunt the hormone surge when the system is actively stimulated? In healthy men given corticotropin-releasing hormone, ACTH and cortisol responses were almost identical with DSIP and with placebo. In ten more men, DSIP did not change the normal midday rise in ACTH and cortisol after a meal. The authors concluded their data do not support DSIP as an inhibitor of ACTH or cortisol in humans.
What the three studies add up to
Together, fewer than 50 healthy men took part, all receiving DSIP by vein under medical supervision. A short-lived ACTH dip appeared in two studies, cortisol never moved, and no study measured stress, anxiety, or how anyone felt. None tested people with chronic stress, women, older adults, or the nasal and under-the-skin products sold online today.
Cortisol also is not a dial that should simply be turned down. It follows a daily rhythm, and both too much and too little cause real illness.
If you suspect a cortisol problem, such as unexplained weight gain with high blood pressure, or exhaustion with weight loss and dizziness, ask a doctor about proper testing, which is timed and interpreted carefully. For everyday stress and poor sleep, the evidence favors sleep habits, physical activity, and talking therapies over a peptide whose stress-hormone record is mostly a null result. Not medical advice.
Sources
- Bjartell A et al. Reduction of immunoreactive ACTH in plasma following intravenous injection of delta sleep-inducing peptide in man. Psychoneuroendocrinology, 1989 (PubMed)
- Chiodera P et al. Different effects of delta-sleep-inducing peptide on arginine-vasopressin and ACTH secretion in normal men. Horm Res, 1994 (PubMed)
- Spath-Schwalbe E et al. Delta-sleep-inducing peptide does not affect CRH and meal-induced ACTH and cortisol secretion. Psychoneuroendocrinology, 1995 (PubMed)
- MedlinePlus: Cortisol test
Related reading
- The thin insomnia trials behind DSIP sleep claims
- DSIP and withdrawal: two 1980s hospital reports
- What DSIP did to anesthesia monitors in surgery
By The Everyday Brief. AI-assisted drafting with automated source and editorial checks. Sources fetched 2026-10-22 PT. Not medical advice.