Cold showers don’t sound more appealing to me as they do to the next man. But I had come across the advice to take a daily cold shower several times – mostly by life coaches talking about discipline, feeling your body and „so many other benefits “. I was despaired for things to change for the better and a daily cold shower sounded like drastic action. Still, I stick to the habit because I am under the impression that it does make me feel better. Then I wanted to read up upon the physiological mechanisms, however, I was surprised how little research was done on cold water effects on mental health.
A study from 2021 reported that 107 people that participate in winter bathing, a tradition in Italy, had higher self-perceived psycho-physical well-being than 121 of the onlookers (1). While this finding indicates a great starting point for further investigation, I had to go back decades to find evidence based data.
In 1988 changes in opioid concentration in different body parts of rats that regularly swam in cold water. These are opioids that the body produces itself. Most prominent among them was beta-endorphin, which is associated with hunger, pain and overall stress reduction and maintaining homeostasis. Beta-endorphin was hugely increased in the hypothalamus and the blood but reduced in the pituitary compared to control group (2). An imbalance of beta-endorphin in the hypothalamus and pituitary has been described in the pathogenesis of depression. Generally, it is believed that people with depression are beta-endorphin deficient (3). So, changing beta-endorphin levels seems to be one way in which cold showers help our mental health.
The sympathetic nervous system is activated under stressful conditions, usually followed by the activation of the parasympathetic nervous system to „heal and digest “. An agent for the sympathetic nervous system is the hormone noradrenaline, that is greatly increased in people suffering from depression (4). In 1996 a study administered healthy men with regular cold treatment. They concluded that the sympathetic nervous system is still significantly (*) activated by noradrenaline and adrenaline after several weeks of cold treatment, comparing the unfilled column with the following hatched column you see in figure 1. However, if you only observe the unfilled columns, there seems to be a trend towards a less a active sympathetic nervous system before the cold treatment after a few weeks into the experiment (5).
In PTSD the sympathetic nervous system is way to active and the parasympathetic nervous system doesn’t get much time to „heal and digest “. There is a hypothesis that says deliberate activation of the sympathetic system and then giving your body the opportunity to calm down/warm up again can help to bring back the normal balance between the two nervous systems.
Again, I cannot believe how few publications I found on the benefits of regular cold showers, specially when past research has shown that there is potential for it to help with depression and PTSD. Maybe no-one wants to know because no practitionerTM wants to make the unpopular suggestion to take regular cold showers. However unappealing it might sound, I am determined to heal. Good lifestyle choices go such a long way.
(4) Catecholamines in depression: an update (1994) Potter WZ, Manji HK.
