REALLY?

LITTLE ROCK — Does taking a “blood thinner” make a person feel colder? Does blood thin when people move to a warm climate, making them feel colder if they move back north?

Changes in perception of heat and cold are highly individual, but “the thickness or viscosity of our blood has nothing to do with how we experience the temperature,” said Holly S. Andersen, director of education and outreach for the Perelman Heart Institute at New York-Presbyterian/Weill Cornell Medical Center.

A blood thinner works by slowing or impairing the blood’s ability to clot, Andersen said, and will not make someone feel colder.

Being exposed to high altitudes, where there is less oxygen, can make blood become a little thicker over time because the bone marrow will produce more red blood cells, which carry oxygen, she said. This may help endurance athletes, she said, but it will not make them feel warmer.

However, she said, “Our body’s ability to control temperature or thermo-regulate does involve blood circulation. In the cold, the small blood vessels on the surface of our body get smaller to keep warm blood deeper inside. In the heat, they dilate to release heat from the body. If you have been in a warm climate for a long time and return to a cold one, it may take a little longer for your circulation to adjust.”

Overall, how warm or cold a person feels “has more to do with our perception of temperature than with our actual temperature,” she said. “A 60-degree day in January feels hot, while in August, it feels mighty cold.”