What happens
Skin cold receptors fire rapidly, triggering an involuntary inhalation, hyperventilation and a sharp rise in heart rate and blood pressure. It typically peaks within the first 30 seconds and settles over the first few minutes.
What research suggests
The response is well characterised in immersion physiology literature and is the primary reason sudden entry into cold water carries drowning risk.
What we don't know
How quickly individuals habituate varies widely, and personal risk factors are hard to predict in advance.
Watch alongside this
Research
Structured sources (title, authors, publication, DOI, evidence rating, review date) load here once research ingestion is connected. No studies are fabricated in the meantime.