When the normal body temperature changes, the affected protein that sends electrical signal for muscle contraction in the heart no longer functions normally.

When the normal body temperature goes up, for example during exercise, or goes down during sleep, the affected protein no longer functions normally. The disrupted protein function causes the electrical signal in our heart to become erratic, triggering an arrhythmia and, potentially, resulting in sudden cardiac death.
Ruben advised, "With this new knowledge, people can examine their family histories and, if sudden cardiac death is part of that family history, or if they suffer from unexplained fainting, they can seek medical advice."
The research team explained, "Temperature fluctuations modify the way all proteins behave, but some DNA mutations can make proteins especially sensitive to changes in temperature. Through a combination of electrocardiograms, genetic screening, and lifestyle management, some tragic deaths caused by cardiac arrhythmia may be prevented."
The study is published in the Journal of Physiology.
Source-IANS