A Scientific Overview of cold-water therapy immersion techniques for improving sleep.

Cold exposure has been suggested to improve sleep quality and reduce time taken to get to sleep. This is through lowering core body temperature and increasing parasympathetic nervous system activity which is the rest and digest division of the nervous system. However, we would like to make it clear this is an emerging area of research which requires further studies. Here is a comprehensive breakdown of recent reports and findings on cold exposure and sleep:

1. Study – 3-min whole body cryotherapy/cryostimulation after training in the evening improves sleep quality in physically active men.

Objective:

The present study aimed to examine the effect of whole-body cryotherapy exposure after training in the evening on sleep quality and night heart rate variability.

Theory:

• The decreased body temperature caused by whole body cryotherapy could have an impact on the time it takes for a person to fall asleep.

• Reduced skin temperature may lead to whole body cryotherapy having analgesic effects by reducing delayed muscle onset soreness which facilitates sleep quality.

• Whole body cryotherapy may also have the power to adjust circadian rhythm and biological clock disturbances caused by high intensity exercise close to bedtime.

Findings:

Whole body cryotherapy improved perceived sleep quality and morning states. It also improved objective sleep quality by reducing the number of movements during sleep. Finally, enhanced pain relief and the parasympathetic nervous activity during deep sleep.

(Douzi et al, 2019)

2.  Study – Effect of the Depth of Cold-Water Immersion on Sleep Architecture and Recovery Among Well-Trained Male Endurance Runners. Randomised Control Trial.

Objective: The aim of the present study was to investigate the effect of the whole-body cold-water immersion vs partial body cold water immersion after high-intensity, intermittent running exercise on sleep architecture and recovery kinetics among well-trained runners.

Theory: 

Whole-body cold-water immersion will lead to a greater reduction in core body temperature which will reduce the time taken to get to sleep and improve sleep propensity resulting in overall greater sleep quality.

Findings:

Whole-body cold-water therapy immersion reduced limb movement and enhanced deep sleep proportion during the first part of the night. However, further studies are required to assess if these positive sleep outcomes would result in overall optimisation of recovery.

(Chauvineau et al, 2021)

3. Cryotherapy on Subjective Sleep Quality, Muscle, and Inflammatory Response in Chinese Middle- and Long-Distance Runners After Muscle Damage.

Objective:

The purpose of this investigation was to explore the effects of cold-water immersion, contrast-water therapy, and whole-body cryotherapy on subjective sleep quality, muscle damage markers, and inflammatory markers in middle- and long-distance runners after muscle damage.

Theory: Cold exposure reactivates the parasympathetic nervous system and blunts sympathetic nervous activity.

Findings: The results from this study suggest that the cryotherapy group saw the greatest improvement in subjective sleep quality and reduced muscle damage.

(Qu et al, 2022) 

Conclusion:

These studies highlight the potential beneficial impact of cold therapy techniques on sleep. Additionally, they further demonstrate cold exposures’ potential to enhance recovery, as sleep increases the release of growth hormone allowing for muscle repair and cell regeneration. Finally, these studies all have a small sample size further highlighting the need for large scale studies in this area.

References:

• Douzi, W., Dupuy, O., Tanneau, M., Boucard, G., Bouzigon, R., & Dugué, B. (2019). 3-min whole body cryotherapy/cryostimulation after training in the evening improves sleep quality in physically active men. European journal of sport science, 19(6), 860–867. https://doi.org/10.1080/17461391.2018.1551937
• Chauvineau, M., Pasquier, F., Guyot, V., Aloulou, A., & Nedelec, M. (2021). Effect of the Depth of Cold Water Immersion on Sleep Architecture and Recovery Among Well-Trained Male Endurance Runners. Frontiers in sports and active living, 3, 659990. https://doi.org/10.3389/fspor.2021.659990
• Qu, C., Wu, Z., Xu, M., Lorenzo, S., Dong, Y., Wang, Z., Qin, F., & Zhao, J. (2022). Cryotherapy on Subjective Sleep Quality, Muscle, and Inflammatory Response in Chinese Middle- and Long-Distance Runners After Muscle Damage. Journal of strength and conditioning research, 36(10), 2883–2890. https://doi.org/10.1519/JSC.0000000000003946