Dry Cold Plunge (Cold Water Immersion): Clinical Evidence

Dry Cold Plunge

(CWI = cold water immersion)

Stress Reduction and Mental Health

A systematic review and meta-analysis (11 RCTs, n = 3,177) found a significant stress reduction at 12 hours post-CWI (SMD: −1.00, p < 0.01), though no significant effects at other time points. Improvements in sleep quality and quality of life were also observed, but not mood. An acute CWI study showed reduced negative affect at 3 hours and lower cortisol levels, though β-endorphins did not change.

The mental health evidence remains largely anecdotal and observational; a formal systematic review protocol has been registered but results are pending.

Metabolic Health and Brown Adipose Tissue

Cold exposure activates brown adipose tissue (BAT) and increases energy expenditure. A meta-analysis of 10 RCTs found acute cold exposure at 16–19°C increased energy expenditure by ~188 kcal/day, with significant increases in BAT volume and activity. Six weeks of daily 2-hour cold exposure at 17°C increased BAT activity and produced a 5.2% reduction in body fat mass. Repeated cold exposure also improved insulin sensitivity and postprandial glucose handling. The molecular pathway converges on PGC-1α, a master regulator of mitochondrial biogenesis, which upregulates UCP-1, antioxidant enzymes, and fatty acid oxidation.

Cardiovascular Effects

A meta-analysis of 24 studies found CWI significantly enhances parasympathetic tone: increased RMSSD (+0.61), HF power (+0.46), and decreased heart rate (−0.16), with slightly increased mean blood pressure (+0.28). These vagal effects persisted up to 15 minutes post-exposure. However, the American Heart Association scientific statement cautions that cold exposure triggers peripheral vasoconstriction, increased blood viscosity, and elevated myocardial oxygen demand, which can be dangerous in individuals with underlying cardiovascular disease.

*Safety Concerns

The ACSM consensus statement identifies four stages of cold water hazard, with the cold shock response being the most dangerous — it produces a 2–3 L involuntary gasp (exceeding the lethal drowning volume of 1.5 L), hyperventilation, hypertension, and increased cardiac workload, peaking in the first 30 seconds. Sudden face immersion can trigger autonomic conflict (simultaneous sympathetic and parasympathetic activation), producing potentially fatal arrhythmias. Patients with cardiovascular disease, uncontrolled hypertension, Raynaud's phenomenon, or cold urticaria should avoid CWI.

References

Cain, T., Brinsley, J., Bennett, H., Nelson, M., Maher, C., & Singh, B. (2025). Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis. PloS one, 20(1), e0317615. https://doi.org/10.1371/journal.pone.0317615

**Castellani, J.W., Eglin, C.M., Ikäheimo, T.M., Montgomery, H., Paal, P., Tipton, M. J. (2021). ACSM expert consensus statement: Injury prevention and exercise performance during cold-weather exercise. Current Sports Medicine Reports, 20(11):p 594-607, | DOI: 10.1249/JSR.0000000000000907

Hanneman, K., Alahmad, B., Ghosh, A., et al. (2026). Nonoptimal temperature and cardiovascular health: A scientific statement from the American Heart Association. American Heart Association Journal, 153(16). https://doi.org/10.1161/CIR.0000000000001419

Harb E, Kheder O, Poopalasingam G, Rashid R, Srinivasan A, Izzi-Engbeaya C. Brown adipose tissue and regulation of human body weight. Diabetes Metab Res Rev. 2023;39(1):e3594. https://doi.org/10.1002/dmrr.3594

Hohenauer, E., Douzi, W., & Burtscher, J. (2025). Potential health benefits of cold-water immersion: the central role of PGC-1α. The Journal of physiology, 10.1113/JP289536. Advance online publication. https://doi.org/10.1113/JP289536

Huo, C., Song, Z., Yin, J., Zhu, Y., Miao, X., Qian, H., Wang, J., Ye, L., & Zhou, L. (2022). Effect of Acute Cold Exposure on Energy Metabolism and Activity of Brown Adipose Tissue in Humans: A Systematic Review and Meta-Analysis. Frontiers in physiology, 13, 917084. https://doi.org/10.3389/fphys.2022.917084

Ivanova, Y. M., & Blondin, D. P. (2021). Examining the benefits of cold exposure as a therapeutic strategy for obesity and type 2 diabetes. Journal of applied physiology (Bethesda, Md. : 1985), 130(5), 1448–1459. https://doi.org/10.1152/japplphysiol.00934.2020

Jdidi, H., Dugué, B., de Bisschop, C., Dupuy, O., & Douzi, W. (2024). The effects of cold exposure (cold water immersion, whole- and partial- body cryostimulation) on cardiovascular and cardiac autonomic control responses in healthy individuals: A systematic review, meta-analysis and meta-regression. Journal of thermal biology, 121, 103857. https://doi.org/10.1016/j.jtherbio.2024.103857

**Knechtle, B., Waśkiewicz, Z., Sousa, C. V., Hill, L., & Nikolaidis, P. T. (2020). Cold Water Swimming-Benefits and Risks: A Narrative Review. International journal of environmental research and public health, 17(23), 8984. https://doi.org/10.3390/ijerph17238984

Reed, E. L., Chapman, C. L., Whittman, E. K., Park, T. E., Larson, E. A., Kaiser, B. W., Comrada, L. N., Wiedenfeld Needham, K., Halliwill, J. R., & Minson, C. T. (2023). Cardiovascular and mood responses to an acute bout of cold water immersion. Journal of thermal biology, 118, 103727. https://doi.org/10.1016/j.jtherbio.2023.103727

**Tipton, M. J., Collier, N., Massey, H., Corbett, J., & Harper, M. (2017). Cold water immersion: kill or cure?. Experimental physiology, 102(11), 1335–1355. https://doi.org/10.1113/EP086283

Yoneshiro, T., Aita, S., Matsushita, M., Kayahara, T., Kameya, T., Kawai, Y., Iwanaga, T., & Saito, M. (2013). Recruited brown adipose tissue as an antiobesity agent in humans. The Journal of clinical investigation, 123(8), 3404–3408. https://doi.org/10.1172/JCI67803