Best Peptides for HRV & Autonomic Recovery: What Actually Moves the Number (2026)

The compounds most used for HRV in our community are the anxiolytic peptide Selank and the sleep peptide DSIP, followed by BPC-157 — but HRV is a biometric your watch and our app measure every night, and the honest truth is that no compound here has ever been shown to raise it in a human, while your sleep, your stress, and your training load move it a lot. This is the recovery-biometric page of the endurance cluster: it answers what the HRV-trackers in our community actually reach for, explains the autonomic physiology that genuinely sets your HRV, and is blunt about where compounds sit in that picture.

HRV — heart-rate variability — is the rare wellness target that is also a hard, trackable number. Your watch reports it each morning, your readiness or recovery score is largely built on it, and you can watch it fall after a bad night, a hard session, or a few drinks. That makes it the perfect place to be honest. Most "peptides for HRV" content either confuses HRV with unrelated natriuretic peptides or quietly implies these compounds lift the number; we do neither. The headline ranking below is first-party usage data — what ~2,600 ProtocolPlus users tracking HRV and readiness actually log — and we keep it strictly separate from the physiology of what moves HRV and the evidence (or absence of it) behind each compound. For the deep science on any molecule we link up to its guide; for sleep specifically we link to the sleep page; for the broad recovery picture we link up to the endurance hub.

Key Takeaways

• What the community uses (not an efficacy ranking): across ~2,600 ProtocolPlus users tracking HRV and readiness, the top three are Selank (18%, 468 users), DSIP (16%, 416), and BPC-157 (14%, 364) (ProtocolPlus app data).
• HRV is driven mostly by sleep, stress, and training load — not by any compound here. Sleep deprivation measurably lowers HRV (RMSSD pooled SMD −0.24) and shifts you sympathetic; overtraining suppresses parasympathetic tone; even one extra drink the night before cuts HRV by roughly 3–4 ms. Fix those first.
• No compound here has a human trial showing it raises HRV. The only human peptide×HRV trial in this group — DSIP given under anaesthesia — found HRV decreased. Everything else is anxiety, sleep, or recovery data used as a surrogate, mostly animal or region-specific.
• The picks target the real levers indirectly: Selank/Semax aim at stress and parasympathetic tone, DSIP/Epitalon at sleep depth, and BPC-157/MOTS-c/NAD+ at recovery — the inputs to HRV, not HRV itself.
• Free things beat the peptides here. Slow paced breathing at about six breaths per minute acutely raises vagally-mediated HRV in humans — more proven than any compound on this page, and free.
• Most of this list survives the drug-tested filter. Only BPC-157 and MOTS-c are WADA-prohibited; Selank, DSIP, Epitalon, Semax, and NAD+ are not currently listed (but unapproved substances can fall under WADA's S0 catch-all — verify before competing).

What peptides does the ProtocolPlus community use for HRV?

Across ~2,600 ProtocolPlus users who track HRV and readiness, Selank is the most-tracked compound (18%), just ahead of the sleep peptide DSIP (16%), with BPC-157 third (14%). This is a usage ranking from our own app data, not a clinical verdict on what raises HRV, and the pattern is revealing on its own.

The split makes sense once you see the logic HRV-trackers follow. HRV reflects autonomic balance — how much your calming, parasympathetic ("rest and digest") system is in charge versus your activating, sympathetic ("fight or flight") system — so the community reaches first for the compounds that touch the two biggest levers on that balance: stress and sleep. Selank leads because it is the anxiolytic, calm-the-nervous-system bet; DSIP is right behind it because sleep quality is the single largest overnight driver of HRV. BPC-157 in third is the recovery/gut-brain bet. After that, usage spreads into a tail of recovery and longevity compounds: NAD+ and MOTS-c (12% each), then Epitalon and Semax (10% each), and the oral metabolic outlier 5-amino-1MQ (8%).

These shares come only from our community-usage dataset and describe behavior, not efficacy. Because HRV is a measurable number our own app reports, this is one of the cleanest goals to compare usage against evidence — and the comparison is humbling: the most-tracked compounds are also among the least-evidenced for actually moving HRV. Read the chart below as "what HRV-trackers reach for," then cross-check it against the physiology and the evidence read further down.

Citation capsule. Among ~2,600 ProtocolPlus users who logged HRV/readiness as a goal, the most-tracked compounds were Selank (18%, 468 users), DSIP (16%, 416), and BPC-157 (14%, 364), then NAD+ (12%, 312), MOTS-c (12%, 312), Epitalon (10%, 260), Semax (10%, 260), and 5-amino-1MQ (8%, 208). This is first-party usage data reflecting what the community uses, not a clinical efficacy ranking and not a safety ranking. Source: ProtocolPlus app data (goals/hrv.json), 2026.

The community's top picks for HRV (by usage)

The community's three most-tracked HRV compounds are Selank, DSIP, and BPC-157 — one anxiolytic, one sleep peptide, and one recovery peptide. Each card pairs the usage share with the honest reason HRV-trackers pick it and the caveat that comes with it.

These three account for roughly 48% of HRV usage in our cohort. The split tells you what HRV-trackers are betting on: the autonomic inputs to the number rather than the number itself. Selank targets the stress/parasympathetic side, DSIP the sleep side, and BPC-157 the recovery side — which is the logical map of what moves HRV. Notice what none of them is: a compound with a human trial showing HRV actually rose. Every pick here is a surrogate bet — calmer, better-rested, better-recovered, therefore (the hope goes) higher HRV.

The long tail (ranks 4–8): the remaining ~52% of usage spreads across the recovery cofactors NAD+ (12%) and MOTS-c (12%), the circadian/longevity peptide Epitalon (10%), the nootropic Semax (10%), and the oral metabolic outlier 5-amino-1MQ (8%). NAD+ and MOTS-c are the cellular-recovery bets (MOTS-c is WADA-prohibited; NAD+ is not); Epitalon targets the melatonin/circadian axis for sleep depth; Semax is the stress-resilience nootropic; and 5-amino-1MQ is the metabolic-energy oddball with no HRV rationale at all. Each gets a mini-section below, with a link up to its full guide.

What actually sets your HRV (the physiology compounds are trying to shortcut)

HRV is a readout of your autonomic nervous system — specifically how much vagal, parasympathetic "rest and digest" tone is running your heart between beats — and the levers that move it most are sleep, stress, training load, alcohol, breathing, and age, not anything in a vial. Understanding that is the fastest way to see why the community's bets are indirect by design, so this is where the recovery-biometric page goes deep.

Your heart does not beat like a metronome. Between beats the interval flexes, mostly under the control of your vagus nerve — when parasympathetic tone is high (relaxed, recovered, asleep), the beat-to-beat interval varies more, and HRV is high; when sympathetic tone takes over (stressed, sick, overtrained, mid-effort), the variation shrinks and HRV drops. The metric most watches and recovery apps lean on is RMSSD, the root-mean-square of successive differences between beats, which closely indexes that vagal, parasympathetic activity and works well on the short overnight or morning recordings wearables use (Shaffer & Ginsberg, "An Overview of Heart Rate Variability Metrics and Norms," Frontiers in Public Health, 2017, retrieved 2026-06-17). A sustained drop in RMSSD is one of the earliest signs you are accumulating fatigue faster than you are recovering.

Why walk through this instead of just listing compounds? Because once you can name the real levers, every claim sorts itself. There are roughly six, and HRV is the integrated product of all of them:

• Sleep is the biggest overnight driver. A 2025 systematic review and meta-analysis found that sleep deprivation lowers vagal HRV (RMSSD pooled SMD −0.24, p<0.05) and pushes the autonomic balance toward sympathetic dominance (LF/HF SMD +1.47, p=0.0007) (Frontiers in Neurology, 2025, retrieved 2026-06-17).
• Training load matters in both directions: fitness raises resting HRV over months, but acute overload suppresses it. A meta-analysis of pre-competition overload periods found parasympathetic modulation (RMSSD) drops below baseline, tracking fatigue and overreaching (ScienceDirect, 2022, retrieved 2026-06-17).
• Stress shifts you sympathetic in real time, which is exactly the lever the calming peptides target — indirectly.
• Alcohol is a sharp, measurable hit: in a within-person wearable study of nearly 21,000 people, one drink above a person's average cut HRV by about 3.8 ms in women and 3.3 ms in men the following night, while resting heart rate rose (PLOS Digital Health, 2026, retrieved 2026-06-17).
• Breathing is the one acute lever you control directly: slow paced breathing at around six breaths per minute reliably raises vagally-mediated HRV in humans, with or without biofeedback (Laborde et al., Psychophysiology, 2022, retrieved 2026-06-17).
• Age lowers baseline HRV: RMSSD norms fall from roughly 55–105 ms in the teens and twenties to around 30 ms by the sixties (normative figures vary by dataset).

The catch the community ranking hides: every compound here aims at one of these inputs — usually sleep or stress — and hopes HRV follows. None acts on HRV directly, and none has been shown to.

The autonomic logic: where each peptide plausibly fits

Map the picks onto the levers and the cohort makes sense. The stress/parasympathetic corner is where Selank and Semax sit — anxiolytic and stress-resilience peptides aiming to quiet sympathetic drive so vagal tone can dominate. The sleep corner is DSIP and Epitalon — DSIP through a (poorly characterised) sleep-promoting mechanism, Epitalon through the pineal/melatonin and circadian axis that governs sleep depth. The recovery corner is BPC-157, MOTS-c, and NAD+ — gut-brain/vagal repair, mitochondrial recovery, and a cellular-energy cofactor, respectively, all betting that a better-recovered body reads as higher overnight HRV. It is a coherent map. What it is not is proof: each of these is a plausible upstream nudge to an HRV input, not a demonstrated effect on HRV.

Why "raise HRV in a pill" keeps coming up empty

Even granting the mechanisms, there is a structural reason these compounds disappoint on the actual number. HRV is a downstream summary of your whole autonomic state on a given night — it integrates how you slept, how stressed you are, how hard you trained, what you drank, and your baseline fitness. A compound that nudges one input (say, marginally deeper sleep) has to clear all the noise of the others to show up in your morning RMSSD, and the honest record is that none of these has been tested with HRV as the endpoint and shown to. The most striking case is DSIP: the single human study that measured HRV after giving it (as an anaesthesia adjunct) found HRV went down and heart rate went up, the opposite of the recovery story. With a hard, measurable endpoint sitting right there, the absence of any positive human HRV data across the whole list is not an oversight — it is the result.

Citation capsule. HRV indexes autonomic balance — high vagal/parasympathetic tone gives high HRV, sympathetic dominance lowers it — and RMSSD is the wearable-friendly vagal index. The biggest movers are sleep (deprivation lowers RMSSD, SMD −0.24, and shifts toward sympathetic, LF/HF +1.47), training load (overload suppresses RMSSD), alcohol (~3–4 ms HRV drop per extra drink), slow paced breathing (~6 breaths/min raises vagal HRV), and age (RMSSD falls with decades). Sources: Frontiers in Neurology 2025 (sleep deprivation meta-analysis); ScienceDirect 2022 (overload/parasympathetic meta-analysis); PLOS Digital Health 2026 (alcohol wearable study, n≈20,968); Laborde et al., Psychophysiology 2022 (slow-paced breathing); Shaffer & Ginsberg, Frontiers in Public Health 2017 (RMSSD/HRV norms). The community's peptides target these inputs indirectly, not HRV itself.

What moves HRV more: sleep, stress, breathing, or these compounds?

On any honest ranking of what raises HRV, sleep and recovering your training load come first, slow paced breathing is a real and free acute lever, fixing alcohol and stress is next — and the compounds the community tracks come in with zero human HRV data, plus one trial that moved HRV the wrong way. This is the honesty visual, and it is the most important chart on the page.

The gap is not subtle. Sleep, training-load management, and slow breathing all have human evidence for moving HRV in the right direction, with real effect sizes attached. Against them, the peptides offer animal or region-specific surrogate data (calmer, better slept) and not a single human HRV measurement that came out positive — while DSIP, the one with a human HRV measurement, came out negative. If your actual goal is a higher HRV number, the chart below is the decision, and the answer is mostly behavioral.

Which HRV compound fits your situation?

The decision turns on three questions the selector asks — what is dragging your HRV down (sleep, stress, or training load), are you drug-tested, and injectable or oral — and unlike the other sport pages, the drug-tested filter here removes only two compounds. The matrix below sets all eight candidates against the dimensions that actually decide it, including which HRV lever they target, route, WADA status, and the column that matters most here: whether any human HRV evidence exists.

This table is the "why" behind the usage ranking, editorial context rather than the headline. The selector quiz at the top runs the same logic interactively, reordering cards toward the sleep, stress, or training-load peptides based on what you say is dragging your HRV down. The drug-tested filter is the sport-specific one, but on this page it behaves differently from the endurance pages: only BPC-157 and MOTS-c are WADA-prohibited, so choosing "drug-tested" keeps most of the list — Selank, DSIP, Epitalon, Semax, and NAD+ all survive (with the S0 caveat). And the "human HRV evidence" column reads the same for every row, which is the honest point of the whole page.

Each candidate, briefly (with where to go deeper)

Here is each of the eight compounds in two to four sentences — enough to place it on the HRV map, with a link up to its full guide for the molecule science. This page owns the "which one for HRV, and why" decision; the mechanism, dosing, and side-effect depth live on each compound's hub, the sleep-specific depth lives on the sleep page, and the broad recovery overview lives on the endurance hub.

Selank

An anxiolytic research peptide (a tuftsin analogue) studied in region-specific trials for anxiety and stress, with mechanisms touching serotonin metabolism, BDNF, and GABAergic signalling. It is the community's most-tracked HRV compound because lowering sympathetic, stress-driven arousal is a logical route to higher vagal HRV — but there is no human trial measuring its effect on HRV, the clinical data is mostly Russian/Ukrainian and research-grade, and it is not currently on the WADA list. Full mechanism and dosing: the Selank complete guide.

DSIP (Delta Sleep-Inducing Peptide)

A peptide named for its sleep-promoting effect in early animal work, tracked here because sleep depth is the biggest overnight lever on HRV. The evidence is old, sparse, and inconsistent, and — critically — the one human study that actually measured HRV after DSIP found HRV dropped and heart rate rose, the opposite of the recovery rationale. It is not currently WADA-prohibited. For the sleep angle specifically, see peptides for sleep; full record: the DSIP guide.

BPC-157

A recovery research peptide with documented gut-brain-axis and vagal-nerve effects in animals, which is the readiness rationale HRV-trackers cite. There is no human HRV evidence, the data is animal only, and BPC-157 is prohibited in sport under WADA's S0 unapproved-substances category. More: the BPC-157 guide.

NAD+

A coenzyme central to cellular energy and repair that declines with age, tracked as a cellular-recovery bet for readiness. The HRV benefit is entirely indirect, there is no HRV evidence, but it is one of the picks that is not currently WADA-prohibited. More: the NAD+ guide.

MOTS-c

A mitochondrial-derived peptide tracked for metabolic recovery after heavy training load, on the theory that better cellular recovery reads as higher HRV. Human data is thin, there is no HRV evidence, and MOTS-c is explicitly WADA-prohibited as an AMPK activator (S4.4) - off-limits if you compete. Unlike the exercise-mimetic SLU-PP-332, which the community tracks for raw endurance rather than HRV, MOTS-c is used here purely on a recovery rationale. More: the MOTS-c guide.

Epitalon

A pineal-axis tetrapeptide tracked for its melatonin/circadian effects, the idea being that deeper, better-timed sleep supports overnight HRV. The longevity claims are largely unreplicated single-group work and the sleep effects are anecdotal; there is no HRV evidence, and it is not currently WADA-prohibited. More: the Epitalon guide.

Semax

A nootropic research peptide tracked for stress resilience, with BDNF/NGF-linked mechanisms and region-specific cognitive-load data. The stress-resilience angle is the HRV rationale, but there is no human HRV trial, the data is region-specific, and it is not explicitly on the WADA list. More: the Semax guide.

5-Amino-1MQ

An oral NNMT inhibitor (not technically a peptide) with a metabolic, energy-adjacent following and no real HRV rationale — it is an outlier on this list. The evidence is mouse data only, there is no HRV evidence, and any HRV claim is extrapolation. Its one practical feature here is that it is the only oral option and is not currently WADA-prohibited. More: the 5-amino-1MQ guide.

The free levers that beat the peptides for HRV

Before any compound, the most reliable ways to raise your HRV are the ones with the best human evidence and the lowest cost — sleep, training-load management, slow paced breathing, and cutting alcohol — and they out-perform everything in the usage chart. If your readiness score is the thing you actually care about, this is the section to act on first.

Start with sleep, because it is the largest overnight lever and the evidence is direct: sleep deprivation measurably lowers RMSSD and shifts you sympathetic, so protecting sleep duration and consistency does more for morning HRV than any vial. Manage training load next — back off when RMSSD trends down for several days, because acute overload suppresses parasympathetic tone, and recovery (not more stimulus) is what brings it back. Use slow paced breathing: a few minutes at around six breaths per minute acutely raises vagally-mediated HRV in humans, with or without a biofeedback device, which makes it the single most evidence-backed, zero-cost HRV intervention available (Laborde et al., Psychophysiology, 2022, retrieved 2026-06-17). And cut alcohol, especially before bed: a within-person study of ~21,000 people found each extra drink lowered next-night HRV by roughly 3–4 ms. None of the peptides on this page has a human HRV result that competes with any of these.

Our take: Read this page as two layers that mostly disagree. The usage chart tells you what HRV-trackers reach for; the physiology and evidence tell you how little supports it. Because HRV is a number your app already measures every night, you do not have to guess — fix sleep, breathe slow, manage load, drink less, and watch your own RMSSD respond before you spend a cent on a research peptide with no human HRV data behind it. The compounds are upstream bets on inputs you can move more reliably for free.

The doping reality for HRV: WADA status by compound

For a drug-tested athlete tracking HRV, the good news is that most of this list is not WADA-prohibited — only BPC-157 and MOTS-c are banned — but "not listed" is not the same as "cleared," because unapproved substances can fall under WADA's catch-all S0 clause. This is the section that matters most if you compete, and it is the one place this page diverges sharply from the endurance pages, where almost everything was banned.

The two clear prohibitions are the recovery peptides. BPC-157 is prohibited at all times under the S0 Unapproved Substances category, and MOTS-c is prohibited as an AMPK activator under S4.4 Metabolic Modulators (USADA, "BPC-157 Peptide Prohibited", retrieved 2026-06-17; USADA, "What is the MOTS-c peptide?", retrieved 2026-06-17). The sleep and stress peptides — Selank, DSIP, Epitalon, Semax — and NAD+ are not currently named on the Prohibited List, which is why the selector's drug-tested filter keeps them. But none of them is an approved medicine, and WADA's S0 clause prohibits any substance not approved by a government health authority for human therapeutic use, so a tested athlete should treat every research peptide here as a potential S0 problem and verify before competing rather than assuming "not listed" means safe.

Citation capsule. Of the eight HRV community picks, two are WADA-prohibited: BPC-157 (prohibited at all times under S0, Unapproved Substances) and MOTS-c (S4.4, Metabolic Modulators, AMPK activator). Selank, DSIP, Epitalon, Semax, and NAD+ are not currently named on the Prohibited List, but WADA's S0 clause can capture any non-approved substance, so tested athletes must verify status before use. Sources: USADA advisories on BPC-157 and MOTS-c; WADA Prohibited List S0 / S4.4. Drug-tested athletes should assume a substance is prohibited unless verified.

What the community does is not what raises HRV

Treat the usage ranking as a popularity signal shaped by mechanism appeal and availability, not as evidence that any of these raises HRV — because the one thing a measurable biometric lets you check, a positive human HRV effect, is missing for every compound on this page. The sharpest tell is that the community's #2 pick, DSIP, is the only one with a human HRV measurement at all, and that measurement was negative.

Three honest framings sit on top of every number here. First, no compound on this page has a human trial showing it raises HRV — the picks lean on anxiety, sleep, or recovery surrogates (mostly animal or region-specific), not HRV measurements, and the single human HRV measurement in the group (DSIP under anaesthesia) found HRV fell. Second, the real levers are behavioral and largely free — sleep, training-load recovery, slow breathing, and less alcohol all have direct human HRV evidence that none of these compounds can match. Third, research-grade vials carry quality risk — unknown potency, purity, and sterility — layered on top of compounds that are already unproven for the goal, and two of them (BPC-157, MOTS-c) will fail a drug test. The biometric framing cuts both ways: because your app measures HRV, you can verify behavioral changes work; you cannot verify a peptide works, because there is no human HRV signal to point to.

Go deeper: the hub and the sibling spokes

This page owns the HRV and autonomic-recovery biometric on purpose — your sleep, your sport, and your broader recovery each have their own focused guide that inherits this page's honest framing. Start with the hub for the full recovery overview, or a sibling spoke for your context.

For the stress and cognition angle that overlaps the most with HRV-trackers' Selank and Semax bets, see peptides for focus and stress. And before sourcing anything, read how to vet peptide quality and are peptides legal.

Who should not go near these

These compounds are not for anyone competing under drug testing without verification, not for anyone outside research or clinical oversight, and none is a substitute for fixing the sleep, stress, and training-load drivers of HRV first. The honest contraindication list here is short and firm.

A few hard lines. Drug-tested athletes must treat BPC-157 and MOTS-c as a failed test waiting to happen, and every other peptide here as a possible S0 problem to verify before competing — "I didn't know" is not a defence. Anyone reaching for a compound before behavior should reconsider: with sleep, breathing, load, and alcohol carrying the real human HRV evidence, a research peptide with none of it is the wrong first move. And for every research compound here, the responsible answer is the same: there is no validated safe-use protocol for raising HRV, so they belong in a trial or under a clinician, not in a self-directed cycle. None of this page is a substitute for that conversation.

Frequently Asked Questions

The bottom line

If you came here for a single "best peptide for HRV," the honest answer is shaped by the fact that HRV is a biometric your app measures every night: there is no peptide with human HRV evidence behind it, and the one human HRV measurement in this group (DSIP) went the wrong way. The community's most-tracked options — Selank for stress, DSIP for sleep, BPC-157 for recovery — are coherent bets on the inputs to HRV, but each is a surrogate, not a demonstrated effect on the number, and the data behind them is animal or region-specific.

For a drug-tested athlete the practical news is better than on the rest of this cluster: only BPC-157 and MOTS-c are clearly prohibited, so most of the list survives the filter — though every research peptide still carries the S0 caveat to verify. The selector at the top narrows the field to your constraints, but the most defensible HRV decision is the one the honesty chart keeps pointing to: protect your sleep, manage your training load, breathe slow, drink less, and watch your own RMSSD respond before betting on a compound with no human HRV data. From here, the natural next reads are the endurance hub for the full recovery field, the sleep page for the biggest lever, and, before sourcing anything, how to vet peptide quality.

Sources

• Frontiers in Neurology. "Effects of sleep deprivation on heart rate variability: a systematic review and meta-analysis." 2025 (PMC12394884). RMSSD pooled SMD −0.24 (95% CI −0.47, −0.00); LF/HF SMD +1.47 (0.62, 2.33). Retrieved 2026-06-17. https://pmc.ncbi.nlm.nih.gov/articles/PMC12394884/
• Pre-competitive overload and parasympathetic modulation: systematic review and meta-analysis. Physiology & Behavior / ScienceDirect, 2022. Overload suppresses RMSSD below baseline, tracking fatigue/overreaching. Retrieved 2026-06-17. https://www.sciencedirect.com/science/article/abs/pii/S0031938422000877
• PLOS Digital Health. Real-world wearable study of alcohol, resting heart rate, and HRV (within-person, n ≈ 20,968; ~5.1M person-days). One drink above average lowered next-night HRV ~3.8 ms (women) / ~3.3 ms (men). 2026. Retrieved 2026-06-17. https://journals.plos.org/digitalhealth/article?id=10.1371%2Fjournal.pdig.0001284
• Laborde S, et al. "Effects of voluntary slow breathing on heart rate and heart rate variability: A systematic review and a meta-analysis." Psychophysiology, 2022. Slow paced breathing (~6 cycles/min) increases vagally-mediated HRV. Retrieved 2026-06-17. https://onlinelibrary.wiley.com/doi/10.1111/psyp.13952
• Shaffer F, Ginsberg JP. "An Overview of Heart Rate Variability Metrics and Norms." Frontiers in Public Health, 2017, 5:258 (PMC5624990). RMSSD indexes vagal/parasympathetic tone and is suited to short recordings. Retrieved 2026-06-17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5624990/
• PubMed. "Delta sleep-inducing peptide alters bispectral index, the electroencephalogram and heart rate variability when used as an adjunct to isoflurane anaesthesia." 2009 (PMID 19142086). RCT, 24 patients; DSIP at 25 nmol/kg increased heart rate and decreased HRV. Retrieved 2026-06-17. https://pubmed.ncbi.nlm.nih.gov/19142086/
• Frontiers in Pharmacology. "Selank modulates GABAergic and serotonergic gene expression." 2017. Selank mechanism (serotonin, BDNF, GABA-A, enkephalinase). Retrieved 2026-06-17. https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2017.00089/full
• Wikipedia. "Selank" (sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro; tuftsin analogue; Russian anxiolytic trials) and "Semax" (BDNF/NGF nootropic, region-specific data). Retrieved 2026-06-17. https://en.wikipedia.org/wiki/Selank
• Healthspan / AlzDiscovery Cognitive Vitality. Epitalon (Epithalon) evidence reviews — Khavinson tetrapeptide, pineal/melatonin axis, largely unreplicated single-group data. Retrieved 2026-06-17. https://www.gethealthspan.com/research/article/epitalon
• MDPI Pharmaceuticals. "BPC-157 and the brain-gut/gut-brain axis." 2023, 16(5):676. Vagal/gut-brain and nerve-repair effects — animal data. Retrieved 2026-06-17. https://www.mdpi.com/1424-8247/16/5/676
• U.S. Anti-Doping Agency (USADA). "BPC-157 Peptide Prohibited" (S0, Unapproved Substances). Retrieved 2026-06-17. https://www.usada.org/spirit-of-sport/bpc-157-peptide-prohibited/
• U.S. Anti-Doping Agency (USADA). "What Is the MOTS-c Peptide?" (S4.4 Metabolic Modulators, AMPK activator). Retrieved 2026-06-17. https://www.usada.org/spirit-of-sport/what-is-mots-c-peptide/
• World Anti-Doping Agency. "The Prohibited List" — S0 Unapproved Substances; S4.4 Metabolic Modulators. Retrieved 2026-06-17. https://www.wada-ama.org/en/prohibited-list
• ProtocolPlus. "Community goal-usage data: HRV / autonomic recovery" (goals/hrv.json). First-party app data, 2026. n ≈ 2,600 users tracking HRV/readiness. Usage signal, not a clinical efficacy or safety ranking.