When summer temperatures turn homes into ovens, desperate remedies become the norm. One of the most extreme involves sticking briefs, boxers and bras in the freezer, hoping that once worn they will help lower body temperature, and provide lasting relief from the suffocating heat. The idea was also made famous on the big screen, in a classic like “The Seven Year Itch”, where an iconic Marilyn confesses to her neighbor that she stores her underwear in the icebox to survive the scorching Manhattan summers. Glamor aside, is it a truly effective technique?
A short-lived thermal illusion
The refreshment is obviously there, if we wear underwear or t-shirts fresh out of the freezer, but to be honest it is short-lived. Extracting a fabric a few degrees above zero and placing it on the skin generates a burst of superficial freshness that momentarily deceives the skin receptors. This initial sensation, however, is a thermal illusion. A normal pair of briefs or a cotton t-shirt have too little mass to accumulate a significant amount of “negative thermal energy”, and like all fabrics (unless they have been specifically engineered to cool) they reach thermal equilibrium with the skin in a matter of minutes.
Once warmed by contact with the skin, underwear removed from the freezer is not only useless for cooling us, but can even become counterproductive. The rapid temperature change in fact attracts the humidity present in the air of the room, generating a thin condensation on the fibres. A damp and cold fabric prevents sweat from evaporating properly, and since sweat is our body’s cooling system, by preventing its evaporation we also lose the ability to disperse excess heat. Ending up making us feel warmer than we did before wearing the frozen underwear.
The paradox of sudden vasoconstriction
Another aspect to keep in mind when seeking escape from the heat concerns how our body reacts to cold shock. When we apply an icy element to a large area of the body, the thermoreceptors of the skin send a signal to the brain, which responds by activating vasoconstriction: the peripheral blood vessels constrict to avoid the dispersion of heat, channeling the blood towards the internal organs.
To effectively lower the core body temperature, moderate, widespread and prolonged cooling is preferable. For this reason, many medical or sports devices are designed to operate around 10 degrees (some up to 10–20), to promote cooling without inducing marked vasoconstriction. The application of extreme cold (such as clothing fresh out of the freezer) can instead activate skin vasoconstriction and reduce its effectiveness in cooling the body.
The “strategic points” trick: how to really refresh yourself
Even in summer, in short, linen is best left in the wardrobe. However, the freezer can be useful for cooling us down without messing up our body’s cooling mechanisms. The key is to act on the areas of the body that have the greatest number of superficial vessels: applying ice to areas such as the wrists, the sides of the neck or the ankles – taking care to wrap it in a cloth to avoid skin lesions – allows you to cool the blood that flows a few millimeters from the surface of our balls, bringing rapid relief to the entire organism.