Ask a Scientist: Why Are Some People Always Hot and Others Always Cold?

The Scientist: Wolfgang Liedtke, M.D., Ph.D., Duke University Medical Center associate professor neurology and a physician at Duke Pain Clinics

The Answer: If you were to take the core body temperatures of that woman in your office who’s always freezing and the guy who’s constantly turning down the thermostat, you’d likely find that they’re both at—or very close to—37 degrees Celsius (98.6 degrees Fahrenheit). The human body is programmed to stay at this temperature, whether it does that through sweating or shivering or other methods of regulation. Humans themselves, however, just want to be comfortable.

What “comfortable” means to you might be different than what it means to the person right next to you. That’s the beauty of being a highly sentient being who invariably is going to have an emotional response to a physiological state. It’s not just about being hot or cold, it’s about feeling hot or cold.

Fidget much? Fidgeters tend to be “hot” people because they have higher muscle tone.

There are, of course, complex biological underpinnings to whether a person is likely to run hotter or cooler. For one thing, women are more likely than men to be “cold people.” Hormones also play a major role, no surprise. Thyroid hormone helps regulate metabolism, or the burning of fuel by your cells, which leads to the production of heat (thermogenesis). More thermogenesis equals higher temperatures. People with low thyroid hormone often feel cold. Sex hormones matter, too. For instance, women’s body temperature is measurably higher in the days following ovulation. Even leptin, a digestive hormone, can influence thermal equilibrium, as can the adrenal hormones involved in the fight or flight response.

Fidget much? You might be a “hot person.” People who are constantly moving (even a little) have more muscle tone, which results in increased thermogenesis and the constriction of blood vessels within the skin, keeping heat from dissipating out of the body. Fat—unlike animal blubber, which acts as an insulator—can exacerbate your temperature issues either way, by making it harder to let go of heat, or by acting as a virtual cold pack around your body.With all these biological and psychological factors at play, it’s unlikely that any one factor will explain your temperature tendencies. At the end of the day, whichever way you lean, layers are your friend.

MORE: What to Do About Excessive Sweating

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