Cardiac health and cold

Exposure to cold can significantly affect blood flow and activate the sympathetic nervous system, which has implications for cardiac health. During cold immersion, particularly when submerged up to the neck at very low temperatures (around 0 degrees Celsius), there's a significant decrease in blood flow to the brain—by approximately 30-40%—to prioritize blood flow to vital organs like the heart. This is a natural response as the sympathetic nervous system kicks in to maintain survival by ensuring that the heart and muscles get the necessary blood supply, which can temporarily reduce cognitive function as the body focuses on preserving essential processes 1.

For some people, this physiological shift might cause symptoms like dizziness or headaches during cold exposure, indicating the body's effort to allocate blood flow effectively during the stress of cold exposure. This prioritization showcases the importance of the heart over the brain when the body's survival mechanisms are activated 1.