A recent study found that taking a 5-minute bath in cold water can make people feel more active, alert, attentive, proud, and inspired, while also reducing feelings of distress and nervousness. The positive emotions experienced by participants were linked to increased communication between different parts of the brain responsible for attention control, emotion, and self-regulation. The study was published in Biology.
Swimming outdoors and taking cold showers are activities that have become more popular in recent years. People who engage in them typically believe that they are beneficial for their health and that they improve well-being. Recent studies have more or less confirmed that. Cold water exposure triggers various biochemical and physiological reactions in the body that can boost the immune system and improve motor function.
Other studies have also shown that regular swimming in cold water can reduce fatigue, alleviate depressive symptoms, and improve general well-being. Research has indicated that cold water immersion can elevate mood and increase positive emotions. On a biochemical level, exposing the whole body to cold water leads to the release of neurotransmitters like serotonin, dopamine, norepinephrine, which play important roles in regulating emotions, stress, and processing rewards.
Study author Ala Yankouskaya of Bournemouth University and her colleagues wanted to understand how mood changes resulting from cold water immersion might be connected to changes in brain connectivity and interactions between different large-scale brain networks. They conducted a study using a type of brain imaging called magnetic resonance imaging (MRI).
The study involved 39 adult participants who were recruited through advertisements on university campuses and social media platforms (Facebook, Twitter). The participants had to be free from chronic pain, not using medication, have no history of chronic health disorders, not be pregnant, and not have engaged in cold water immersion in the past 12-18 months.
Upon arriving at the laboratory, the participants completed an assessment of their emotions. The researchers then conducted resting-state MRI scans of their brains and recorded a 2-minute electrocardiogram to measure heart activity. After that, the participants immersed themselves in a cold bath (19.93◦C ± 0.13◦C) up to their collarbones for 5 minutes.
After drying and dressing up, they returned for another MRI scan and completed the emotional assessment once again. As compensation for their participation, each participant received a 20 GBP (around $25) Amazon voucher.
The results of the study showed that the cold water bath significantly increased the participants’ heart rate, and their breathing volume remained elevated throughout the bath. Participants reported feeling more positive emotions and fewer negative emotions after the cold water bath compared to before. They described feeling more active, alert, attentive, inspired, proud, and less nervous.
The MRI data analysis identified two clusters of brain connections that showed significant changes.
“All tiny parts of the brain are connected to each other in a certain pattern when we carry out activities in our day-to-day lives, so the brain works as a whole,” Yankouskaya said in a news release. “After our participants went in the cold water, we saw the physiological effects—such as shivering and heavy breathing. The MRI scans then showed us how the brain rewires its connectivity to help the person cope with the shock.”
The first cluster included heightened connectivity between the medial prefrontal cortex and certain regions in the salience network. Specifically, there was stronger coupling between the medial prefrontal cortex and the left anterior insula, left rostral prefrontal cortex, and left lateral parietal part of the default mode network. Interestingly, there was also a negative connection between the medial prefrontal cortex and the anterior cingulate cortex of the salience network.
The default mode network is active during restful wakefulness and is associated with self-reflection and processing internal thoughts and memories. The salience network is involved in detecting and directing attention to important stimuli, integrating sensory and emotional information, and facilitating cognitive control processes.
The second cluster consisted of positive connections between the posterior parietal cortex of the frontoparietal network (associated with attention and cognition), the right inferior parietal sulcus of the dorsal attention network, and the right visual lateral network. These connections also showed significant changes after cold-water immersion.
The increase in positive emotions was found to be associated with altered connectivity involving the medial prefrontal cortex, two nodes of the salience network (anterior cingulate cortex and rostral prefrontal cortex), and connections between different brain regions in the right hemisphere (frontoparietal network, dorsal attention network, and visual lateral network). These brain areas are involved in attention control, emotion, and self-regulation. The reduction in negative emotions did not show strong associations with changes in brain connectivity.
“These are the parts of the brain that control our emotions, and help us stay attentive and make decisions,” Yankouskaya said. “So when the participants told us that they felt more alert, excited and generally better after their cold bath, we expected to see changes to the connectivity between those parts. And that is exactly what we found.”
The study contributes to the scientific understanding of effects of cold water immersion. However, it should be noted that the study did not include a control group. Also, precision mapping of brain networks is not consistent in the literature and minute details about brain networks involved might not be completely accurate.
The study, “Short-Term Head-Out Whole-Body Cold-Water Immersion Facilitates Positive Affect and Increases Interaction between Large-Scale Brain Networks“, was authored by Ala Yankouskaya, Ruth Williamson, Cameron Stacey, John James Totman, and Heather Massey.