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Water immersion thermotherapy significantly increases total sleep time and improves sleep efficiency in healthy adults, but does not significantly affect subjective sleep quality.

This meta-analysis of 10 randomized controlled trials found that water immersion thermotherapy (WIT) significantly increased total sleep time (SMD = 0.63, P = 0.0438) and improved sleep efficiency (SMD = 0.64, P = 0.0419). However, no significant effects were observed on sleep latency or any PSQI subscale, indicating limited overall subjective sleep quality improvement.

Last updated: Aug 15, 2026•0 RCTs•1 Meta-analyses•📖 Read as article →

Evidence Score

Evidence Score58/100
Human RCT☆☆☆☆☆
Meta-analysis★★★☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. The effect of water immersion thermotherapy on sleep quality: a systematic review and meta-analysis of randomized controlled trials.

observational

Chen H, Gao S, Chen W, Gao B · International journal of biometeorology (2026)

Participants: N/A
Duration: N/A
Intervention: Water immersion thermotherapy (WIT) - various protocols including warm baths or immersion
Outcome: Total sleep time, sleep efficiency, sleep latency, PSQI total score and subscales
Effect Size: SMD = 0.63 for total sleep time; SMD = 0.64 for sleep efficiency
Population: Healthy adults (from 10 randomized controlled trials)

Result:

PubMed: 42545422DOI: 10.1007/s00484-026-03281-7

Mechanism Graph

WIT raises core body temperature
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Subsequent cooling triggers vasodilation and heat dissipation
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This promotes sleep onset and maintenance
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Result: Increased total sleep time and sleep efficiency

Limitations

  • ⚠Only 10 RCTs included, with potential heterogeneity in WIT protocols
  • ⚠No significant effect on subjective sleep quality (PSQI), suggesting limited clinical relevance
  • ⚠Publication bias not assessed in the abstract

Frequently Asked Questions

Does water immersion thermotherapy improve sleep quality?▼

It can significantly increase total sleep time and improve sleep efficiency, but does not significantly improve subjective sleep quality as measured by PSQI.

What is the effect size of water immersion thermotherapy on sleep?▼

The standardized mean difference is 0.63 for total sleep time and 0.64 for sleep efficiency, indicating moderate effects.

Which sleep parameters are not affected by water immersion thermotherapy?▼

Sleep latency and all PSQI subscales (including subjective sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disturbances, use of sleep medication, and daytime dysfunction) showed no significant improvement.

Who was included in this meta-analysis?▼

The analysis included 10 randomized controlled trials involving healthy adults.

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References

  1. 1.Chen H, Gao S, Chen W, Gao B. "The effect of water immersion thermotherapy on sleep quality: a systematic review and meta-analysis of randomized controlled trials.." International journal of biometeorology, 2026. PMID: 42545422 DOI: 10.1007/s00484-026-03281-7
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.