Sleep, Stress & Neuropeptides — what studies report on brain–body regulation

From sleep–wake timing to how we cope with pressure, several neuropeptide systems help coordinate brain and body. This plain-English overview summarises study-led findings on orexin/hypocretin, CRH–ACTH stress signalling, and research peptides often discussed in this space.

Key takeaways

Orexin/hypocretin neurons stabilise wakefulness and arousal; low cerebrospinal orexin is a hallmark finding in narcolepsy research.
CRH–ACTH–cortisol signalling links psychological stress to measurable physiology (cortisol, heart-rate variability); CRH generally increases arousal/anxiety-like behaviours in animal models.
Neuropeptide Y (NPY) is repeatedly associated with stress resilience in preclinical work and small human studies.
Compounds like Semax, Selank, and historical DSIP appear in literature and reviews; English-language human datasets are limited and mixed.

What researchers measure

Sleep work commonly uses polysomnography (EEG stages, REM/NREM ratio), actigraphy, and sleep questionnaires (e.g., PSQI). Stress studies track salivary/serum cortisol, heart-rate variability (HRV), validated scales (e.g., STAI), and sometimes cytokines. Lab choices and timing (morning vs evening) strongly affect outcomes.

Study snapshots (systems → readouts → one-line summary)

Orexin/hypocretin (animal & human): Promotes wakefulness and stabilises sleep–wake transitions; low CSF orexin is characteristic in narcolepsy cohorts. PubMed: orexin sleep review
CRH–ACTH axis (animal & human): CRH administration increases arousal/anxiety-like behaviour in animals; human stress reactivity often indexed by cortisol/HRV. PubMed: CRH stress review
Neuropeptide Y: Frequently linked with anxiolytic-like effects and stress resilience; studies explore central and peripheral mechanisms. PubMed: NPY resilience review
Semax/Selank (research peptides): Russian and Eastern-European literature reports cognitive or anxiolytic signals; methodology and generalisability vary; English datasets are limited. Semax review search · Selank review search
DSIP (historical): Early reports suggested sleep effects; modern evidence is inconsistent and often negative in rigorous settings. DSIP review search

Sleep studies focus on architecture and circadian timing; stress studies track cortisol and HRV. Model choice and measurement timing can change conclusions.

What remains uncertain

Human efficacy: many neuropeptide findings come from animal models; well-controlled human trials are fewer and smaller.
Standardisation: variable formulations, routes, and endpoints complicate comparisons across studies.
Translation: results in one population (e.g., sleep-disordered patients) do not automatically generalise to healthy volunteers.