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Key points
- Temperature-sensitive nerve fibers called thermoreceptors help to regulate our body temperature.
- Vasodilation and perspiration are the body's two primary methods for cooling us down.
- Tricks like drinking hot beverages and going barefoot take advantage of these natural cooling systems.
It’s already been a summer of record-breaking heat around the world, and the season isn’t even half over yet.
When temperatures soar above seasonal norms, it leaves all of us scrambling for new ways to beat the heat. Read on for a brief run-down of how temperature sensation works and what steps you can take to feel cooler this summer.
How do we sense heat?
Maintaining a core body temperature between 97° and 100°F (36.1° and 37.8°C) is essential to human health. The ideal body temperature within that range varies slightly from person to person and changes throughout the day, measuring about 0.9°F (0.5°C) lower in the early morning than in the late afternoon. A stable core temperature allows the body to sustain homeostasis, a state of physiological balance where all of its systems can function properly.
To help us maintain our core temperature, we have temperature-sensitive nerve fibers called thermoreceptors throughout our bodies, including in our skin, muscles, and internal organs. The thermoreceptors in our skin are the first line of defense that lets us know when we need to take action to keep from overheating.
The thermoreceptors in your skin don’t give you an objective reading of the temperature of your surroundings, the way a thermometer does. Instead, they let you know whether your skin is warming up or cooling down, and their activity levels off when skin temperature becomes steady again. That’s why water feels colder when you first jump in than it does after a few minutes of swimming, once the temperature of your skin has stabilized.
The body’s natural cooling systems
Our bodies have two natural ways of cooling us down when the temperature rises: vasodilation and perspiration.
Vasodilation is when blood vessels widen, allowing more blood to flow through them. When we’re hot, blood vessels near the surface of the skin dilate, sending more blood to the outer shell of the body where it can lose some heat as long as the external temperature is lower than the body’s core temperature.
This chilled blood is then circulated back in to the center of the body, where it absorbs heat and cools the core. This is essentially the same way refrigerators and car engine cooling systems work: liquid coolant flows through the system, soaking up heat as it goes, and is then circulated out again to be cooled by the surrounding air.
If body temperature continues to rise, we start to sweat. It’s the evaporation of sweat that cools us off. Transforming a liquid into a vapour uses heat energy, and, when sweat evaporates, some of this energy is drawn from the surrounding skin, lowering its temperature.
How to cool off in high heat
Most people know the basics for staying healthy when the mercury rises: drink lots of fluids, wear breathable clothes, and limit exertion until you acclimatize. But we can also harness the body’s own methods for regulating its temperature using some less common tricks.
- Choose hot drinks over cold ones. This won’t come as a surprise to residents of Asian and North African countries where tea is the preferred summer drink, but hot beverages can actually cool you down faster than cold ones. That’s because when thermoreceptors in the stomach sense heat, they increase your sweat output, bringing down your skin temperature more quickly. This trick works best in environments with relatively low humidity, where sweat can evaporate fully.
- Apply cold to pulse points. Apply a cold cloth or run cold water over places where you can easily feel your pulse, like your wrists, neck, inner elbows, or temples, to help your body discharge heat. Veins are closer to the skin at these pulse points, which allows the blood flowing through them to cool down more efficiently before returning to the body’s core.
- Go barefoot. Kick up your bare feet in a hammock or wade in a pond to take advantage of specialized blood vessels in the soles of your feet called arterio-venous anastomoses (AVAs) that play a major role in dissipating body heat. They’re a throwback to our mammalian ancestors who were covered in fur and could only release heat effectively through the non-hairy skin on their paw pads, tongues, and sometimes inner ears.
- Cut down on protein. Ever heard of the meat sweats? Proteins are more complicated to digest than carbohydrates, so your body has to expend extra energy breaking them down. This energy is transformed into heat, something scientists call diet-induced thermogenesis. One study found that skin temperature increased an average of 3.6°F (2°C) after a high-protein meal.
- Eat more fruits and veggies. Enjoy all the produce that’s coming into season at this time of year and cool yourself off at the same time. Fruits and veggies are easy to digest and high in water content, supplying your body with fluid that can be converted into sweat. Melons, peaches, apples, tomatoes, cucumbers, lettuce, and zucchini make great choices due to their high ratio of water per serving.
