Amino AcidsL-Theanine

Walnut peptide and theanine combination (WPT) improves chronic stress-induced sleep disorders by restoring slow-wave sleep duration and quality in adults with poor sleep quality.

In an 8-week randomized, placebo-controlled human trial, WPT restored sleep duration and improved subjective sleep quality scores (PSQI ≥ 7). Mechanistically, WPT reduced serum corticosterone levels and increased GABA and tryptophan in CUMS mice, indicating HPA axis regulation and neurotransmitter modulation.

Last updated: Jul 7, 2026•1 RCTs•📖 Read as article →

Evidence Score

Evidence Score44/100
Human RCT★★☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Walnut peptide and theanine combination ameliorates sleep disorders: a multi-species study including a human trial.

observational

Gong J, Jia X, Wang L, Lu Y, Guo R, Gong R, Hao J, Zhao Z, Duan S, Liu X, He J, Li H, Liu Z · Food & function (2026)

Participants: N/A
Duration: 8 weeks
Intervention: Combination of walnut peptide and theanine (WPT)
Outcome: Sleep duration, subjective sleep quality (PSQI score), sleep architecture (SWS duration, delta wave power density), waking activity, serum corticosterone, GABA, tryptophan
Effect Size: N/A
Population: Adults with sleep disturbances (PSQI ≥ 7), CUMS mice, PTZ-induced zebrafish

Result:

PubMed: 41531275DOI: 10.1039/d5fo03867g

Mechanism Graph

Reduces HPA axis hyperactivity by lowering elevated serum corticosterone
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Increases inhibitory neurotransmitter GABA
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Increases tryptophan, a precursor for serotonin and melatonin
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Restores slow-wave sleep duration and delta wave power density, improving sleep architecture

Limitations

  • ⚠Abstract does not report specific effect sizes or confidence intervals for human outcomes
  • ⚠Human trial sample size and detailed demographics not provided in abstract
  • ⚠Long-term efficacy and safety beyond 8 weeks are not addressed

Frequently Asked Questions

What is WPT?▼

WPT is a combination of walnut peptide and theanine, tested as a nutritional intervention for sleep disorders.

How does WPT improve sleep?▼

It reduces HPA axis hyperactivity by lowering corticosterone levels and increases inhibitory neurotransmitter GABA and tryptophan, a precursor for serotonin and melatonin.

Who was studied in the human trial?▼

Adults with poor sleep quality, defined as a Pittsburgh Sleep Quality Index (PSQI) score of 7 or higher.

What were the main outcomes in humans?▼

Restored sleep duration and improved subjective sleep quality as measured by the PSQI.

Products

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References

  1. 1.Gong J, Jia X, Wang L, Lu Y, Guo R, Gong R, Hao J, Zhao Z, Duan S, Liu X, He J, Li H, Liu Z. "Walnut peptide and theanine combination ameliorates sleep disorders: a multi-species study including a human trial.." Food & function, 2026. PMID: 41531275 DOI: 10.1039/d5fo03867g
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.