Sleep Environment & Hygiene — References

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Parent Topic: Sleep Environment & Hygiene | References Hub: 01 - Foundations References MOC

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Primary Literature & Landmark Studies

Haghayegh et al. (2019)

• Citation: Haghayegh, S., Khoshnevis, S., Smolensky, M. H., Diller, K. R., & Castriotta, R. J. (2019). Before-bedtime passive body heating by warm shower or bath to improve sleep: a systematic review and meta-analysis. Sleep Medicine Reviews, 46, 124–135.
• Identifiers: DOI: 10.1016/j.smrv.2019.04.008 (DOI · SciDB · Scholar) | PMID: 31102877 (PubMed · Europe PMC)
• Study Design: Systematic review and meta-analysis of 17 controlled clinical trials evaluating water-based passive body heating (PBH) on objective polysomnographic and actigraphic sleep parameters.
• Key Quantitative Outcomes:
  • Passive body heating at 40.0–42.5°C scheduled 1–2 hours before bedtime for as little as 10 minutes significantly shortened Sleep Onset Latency (SOL) (standardized mean difference $\text{SMD}=-0.43,p<0.001$, corresponding to a ~36% reduction in SOL), improved sleep efficiency, and increased slow-wave sleep by accelerating core body heat dissipation via distal skin vasodilation.

Strøm-Tejsen et al. (2016)

• Citation: Strøm-Tejsen, P., Zukowska, D., Wargocki, P., & Wyon, D. P. (2016). The effects of bedroom air quality on sleep and next-day performance. Indoor Air, 26(5), 679–686.
• Identifiers: DOI: 10.1111/ina.12254 (DOI · SciDB · Scholar) | PMID: 26517188 (PubMed · Europe PMC)
• Study Design: Two-part randomized crossover field intervention in healthy young adults ($N=30$ across window-ventilation and silent mechanical fan ventilation trials).
• Key Quantitative Outcomes:
  • Lowering nocturnal bedroom ${\text{CO}}_2$ concentrations from a mean of 2,395–2,585 ppm (unventilated) to 660–715 ppm (ventilated) significantly increased actigraphic sleep efficiency ($p<0.01$), decreased number of awakenings ($p<0.05$), reduced next-day sleepiness, and improved Baddeley grammatical reasoning performance ($p<0.02$).

Mason et al. (2022)

• Citation: Mason, I. C., Grimaldi, D., Reid, K. J., Warlick, C. D., Malkani, R. G., Abbott, S. M., & Zee, P. C. (2022). Light exposure during sleep impairs cardiometabolic function. Proceedings of the National Academy of Sciences (PNAS), 119(12), e2113290119.
• Identifiers: DOI: 10.1073/pnas.2113290119 (DOI · SciDB · Scholar) | PMID: 35286195 (PubMed · Europe PMC)
• Study Design: Parallel-group randomized controlled laboratory study in healthy adults ($N=20$; 1 night dim light <3 lux vs. 1 night moderate room light 100 lux during sleep).
• Key Quantitative Outcomes:
  • Sleeping under 100 lux room light significantly reduced N3 slow-wave sleep and REM percentage, elevated nocturnal heart rate ($p<0.01$), increased sympathetic-to-parasympathetic HRV ratio (LF/HF), and increased next-morning HOMA-IR insulin resistance by ~15% alongside higher 30-minute post-OGTT insulin levels ($p<0.05$).

Kräuchi et al. (1999)

• Citation: Kräuchi, K., Cajochen, C., Werth, E., & Wirz-Justice, A. (1999). Warm feet promote the rapid onset of sleep. Nature, 401(6748), 36–37.
• Identifiers: DOI: 10.1038/43366 (DOI · SciDB · Scholar) | PMID: 10485703 (PubMed · Europe PMC)
• Study Design: Controlled laboratory circadian thermoregulation study in healthy young men ($N=18$).
• Key Quantitative Outcomes:
  • Established that the distal-proximal skin temperature gradient (DPG)—reflecting arteriovenous anastomosis vasodilation in hands and feet—was the strongest physiological predictor of sleep onset latency ($r=-0.47,p<0.0001$), outperforming core body temperature rate of change, subjective sleepiness, and melatonin levels.