Controlled exposure to cold water showers or ice bathtubs can reset the immune system as a survival mechanism.

The immune system does not like sharp temperature changes, but this is a different type of relatively prolonged exposure to intense cold in the water. The action activates a survival mechanism that gradually strengthens the immune system through an energetic mechanism similar to deep meditation. It is a technique of personal empowerment - comparable to martial arts. (In a different sense)
Immersion in ice water has the known benefits of releasing endorphins, improving alertness and mood, strengthening the immune system, and even losing weight. (Not because of the need to warm up the body) At the same time, this technique is not without risks.
What are the method's main disadvantages of cold water showers and ice bathtubs?
It is challenging to perform, requires persistence, physical suffering is quite aggressive and is unsuitable for chronic patients in an inadequately energetic state.