Amino AcidsL-Theanine

Walnut peptide and theanine combination (WPT) improves sleep disorders 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 as assessed by the Pittsburgh Sleep Quality Index (PSQI) in adults with PSQI ≥ 7. The intervention also reduced waking activity in zebrafish and restored slow-wave sleep duration and delta wave power density in CUMS mice, while lowering serum corticosterone and increasing GABA and tryptophan levels.

Last updated: Aug 26, 2026•1 RCTs•📖 Read as article →

Evidence Score

Evidence Score42/100
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

WPT lowers elevated serum corticosterone levels
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WPT increases inhibitory neurotransmitter GABA
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WPT increases tryptophan, a precursor for serotonin and melatonin
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Result: Restored slow-wave sleep duration and improved sleep quality

Limitations

  • ⚠Abstract does not specify exact dose of WPT used in the human trial
  • ⚠Abstract does not report effect sizes or confidence intervals for human outcomes
  • ⚠Multi-species design may limit direct translation of animal findings to humans

Frequently Asked Questions

What is WPT?▼

WPT stands for walnut peptide and theanine combination, a nutritional intervention tested for sleep improvement.

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.

How long was the human trial?▼

The human trial lasted 8 weeks and was randomized and placebo-controlled.

What mechanisms did WPT affect?▼

WPT reduced serum corticosterone (a stress hormone) and increased levels of GABA and tryptophan, which are involved in sleep regulation.

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.