If a person is heard to utter the phrase “my blood runs cold,” it is generally meant to imply that he has been scared out of his wits by something either seen, heard, or experienced. The statement really implies far more than mere fright. In most cases the reference would be to abject terror, a dread bordering on hysteria, or an overpowering sense of impending destruction.
Usually, the thought of blood running cold comes about due to actions performed by a human. The description of a heinous crime, a particularly odious comment, or the sight of something hideous could warrant verbalization of such an expression. However, the effect could also arise out of viewing a frightening scene in nature. Coming across a hungry grizzly bear in a deep forest could make a person’s blood run cold. Even a movie, if imbued with enough violence or mayhem, could elicit the sense of blood running cold.
Of course, there could also be a technical aspect involved when a person says that his blood runs cold. Blood in the human body actually freezes at between approximately 23 and 28 degrees Fahrenheit (-2 to -5 degrees Celsius). This is something of a horrifying image in itself, and the thought of your blood freezing solid could cause your blood to run cold if you ponder it too deeply.
“Blood runs cold,” is an idiomatic expression, most likely one of American derivation. It has almost become something of a cliché in books, short stories, and song lyrics. The English rock band, Def Leppard, featured a track on their 1996 “Slang” album entitled Blood Runs Cold. Also, on the internationally best-selling, 1981 album Freeze Frame, the American J. Geils Band included the phrase in the hit single “Centerfold.” Last but far from least, a variation of “blood runs cold” was immortalized by author Truman Capote in his 1966 novel, In Cold Blood.
Then again, if your blood seems to be running a bit cold, you could be suffering the beginning stages of hypothermia. Hypothermia can set it whenever your body core temperature drops below 95 degrees Fahrenheit (35 degrees Celsius). Death from hypothermia takes place when the body’s core temperature drops below 86 degrees Fahrenheit (30 degrees Celsius).
Thus, to avoid your blood running cold, it is advised to dress warmly, avoid murder scenes, abstain from making friends with serial killers, and steer clear of war zones. For some, refraining from repeated viewings of Night of the Living Dead is also a wise policy.