Cold Water Benefits
Cold showers are an accessible starting point for activating the sympathetic nervous system and brown fat. However, submerging in cold water offers greater physiological benefits, including improved blood vessel function and activation of the parasympathetic nervous system. A brief cold shower of just 30 seconds can be effective, but full immersion enhances overall metabolic response and recovery.In this clip
From this podcast

The School of Greatness
Metabolism Expert Reveals The Science of Cold Therapy to BURN Fat FAST! | Susanna Søberg
Related Questions
If you start building up resistance to cold plunges and switch to just cold water showers, are you losing the benefits that you used to have, or is there another benefit, like the activation of brown fat?
What are the benefits of cold showers according to Dr. Susanna Søberg?
How beneficial is a cold shower?