Cold-water immersion as a form of body hardening: a fad or an effective method of improving health? A literature review.

Abstract

Background

Cold-water immersion, defined as voluntary exposure to cold water, has gained popularity as a lifestyle practice aimed at improving immunity, stress resilience, mental well-being, and recovery. Despite plausible mechanisms involving autonomic, endocrine, thermoregulatory, and immune responses, clinical evidence remains heterogeneous and methodologically limited.

Aim of study

This narrative review aimed to synthesize evidence on cold-water immersion as a form of physiological “hardening”, focusing on mechanisms, health effects, and safety, and to assess whether it represents a clinically meaningful intervention or mainly a culturally driven trend.

Material and methods

A narrative review of recent literature with key earlier studies was conducted. Studies in adults exposed to cold-water immersion, cold baths, or cold showers were included. Outcomes comprised physiological parameters (e.g., cardiovascular responses, thermoregulation, inflammatory and immune markers) and subjective measures such as stress, sleep, and well-being, with critical appraisal of study quality and protocol variability.

Results

Cold-water immersion induces an acute multisystem stress response with sympathetic activation, peripheral vasoconstriction, increased heart and respiratory rates, and activation of thermogenesis, including possible brown adipose tissue involvement. Short-term improvements in stress, mood, sleep, and selected cardiometabolic indices have been reported; however, findings are inconsistent, protocol-dependent, and lack evidence of sustained long-term effects. 

Conclusions

Cold-water immersion may elicit adaptive responses and transient benefits in some individuals, but current evidence does not support its classification as a universally effective clinical intervention. Caution is advised, particularly in individuals with cardiovascular or respiratory risk. Further high-quality, long-term studies are needed.