While much of the nation is sweltering under the summer’s intense heat, have you ever wondered how we humans and other animals stay cool when it’s so hot outside?

The simple answer is sweating for humans. But do you know why sweating is an effective way to cool the body?

What You Need To Know

  • Thermoregulation is how we maintain body temperature with tightly controlled self-regulation independent of external temperatures

  • Humans have 2 million sweat glands that produce perspiration

  • Evaporation helps cools the body's temperature

  • Humans could also cool their bodies through convection and conduction

Before we go into the science of how we cool down, let’s review what happens when our body’s air conditioning system kicks into gear. In order to survive, the body controls its own temperature, a process called “thermoregulation”. For humans, the temperature maintained is around 98.6 degrees, give or take a degree or two.

If you’re outside long enough, especially on a hot day when you’re exerting yourself, you perspire or sweat. This is when your body is getting overheated and it needs to cool down.

Have you noticed when you’re sweating and the wind blows it feels refreshing? That’s because the moving air against your moist skin helps evaporate the sweat and it cools you down. That’s why fans are effective.

Your body has over 2 million sweat glands that produce perspiration on the skin’s surface. By using evaporation, your body can lower its temperature relatively quickly.

Here’s how it works. The moisture on your skin is in a liquid state. When it evaporates into the surrounding air, it changes its state to a gas.

This change in state, called evaporation, takes latent (hidden) heat away from the body, cooling the skin. Think about when you take a shower (especially during the colder months) and you get out. You feel chilly.

This is because the water on your skin evaporates, making you feel chilled. The first thing you do is grab a towel to dry off and stop the evaporation process.

As mentioned, evaporation is effective for cooling your body’s temperature. However, when the air is hot and humid or has a lot of water vapor already present, the sweat has a much harder time evaporating. Therefore, you feel so uncomfortable on hot and muggy days.

The sweat ends up not evaporating, instead it rolls off your body and soaks your clothes. This is also why hot and humid days can be dangerous because your body’s built-in air conditioning system may not keep itself cool.

The body temperature ends up getting too high, which can lead to heat stroke and, in extreme cases, death.

Under the stress of keeping your temperature cool, your body can lose a lot of water when sweating for extended periods. So, it’s important to replenish this water by staying hydrated.

On a related note, other animals also used evaporation to keep themselves cool. Dogs, for example, don’t have sweat glands. So, to take advantage of evaporative cooling, they use their tongues through panting.

By moving air over their moist tongue, evaporation cools the surrounding air, which cools their nose and lungs.

Your body has other ways to cool itself down, other than through sweating. Your body also will dilate the blood vessels near the skin’s surface, increasing the blood flow. Through a process called “convection”, we transfer heat from the body to the surrounding air.

Another process called “conduction” is when your body cools itself by transferring some of its own heat to another cooler surface. So next time on a warm summer night, you feel compelled to turn the pillow over to the cooler side… that’s the reason.

So remember, help your body out by giving it some breaks by going inside to allow it to cool down. Drink plenty of water to replenish the water it lost through sweating.

Also, listen to your body. If you felt dizzy, sick to your stomach or get a headache, these are signs your body is losing the battle to stay cool. Get to a cooler place and drink some water.

Also, remember to check on the elderly as older bodies have a harder time staying cool.

Plus, don’t forget about our four-legged friends. They deserve a cool place to stay and plenty of water like we do.