Why Does Heat Make You Tired?

Ever started to feel dizzy after sitting out in the sun for a long time? Most people prefer lounging in hot weather because of this innate feeling.

However, it’s important to understand the science behind this.

Many people understand the basics of getting tired in the heat, but it’s best to start with why the sun continues to play an important role in this.

See 10 ways to stay cool during hot summer nights

Here is more on why heat and the sun make you tired.


sitting out in the sun

A John Hopkins Medical Study illustrated dehydration causes an imbalance between one’s essential body salts and water content. When the body salts start depleting (i.e. sodium, potassium) this can lead to fatigue settling in and cause trouble.

Dehydration becomes prevalent if the body is exposed to hot conditions.

This is the same reason why one starts to feel sapped when walking in the desert. The sun’s reflection off the sand and makes it unbearable without the right clothing and hydration.

Heat impacts the body in a way where it is important to drink water and stay hydrated. Those who don’t will never be at 100% with their energy levels. It is best to stay prepped for this, so the results are based on what one requires.

Remember, the body works 24/7, and that doesn’t change regardless of your state (i.e. fully awake, sitting, or sleeping) because a natural balance has to be maintained. Dehydration is a sign of this natural balance starting to come undone.

By sitting in the heat, this is expedited, and the results can be hampered.

It is better to drink water and ensure enough time is being spent on this aspect of your routine when in hot conditions.

Heart And Metabolic Rate Rise

The next reason why the body can start to feel sapped involves one’s heart and metabolic rate. The body reacts to external conditions and adapts. The idea is to “survive” as that’s the body’s primary goal and it works with the mindset of self-preservation. The same applies to hotter external conditions.

The first reaction to sun exposure or hot weather is for the heart rate to rise. This is done so that the temperature inside the body is maintained. If not, the body will start to fail, and it becomes impossible to function. The metabolic rate is the same as it looks to get the digestive process flowing. This is the only way for the body to stay healthy.

If not, a person will not feel on top of things, and that’s where the body desires rest and going to sleep.

When the heart rate remains up for an extended period (i.e. hours), the body starts functioning at a lower pace. This is a given and is the reason work has to be done to rest and slow down as the weather increases.


It’s the same when the weather is frigid. The body does its best to increase the heart rate, so it warms up.

Chemical Changes

The final reason involves chemical changes in the body when the weather is warm. These chemical changes come as a natural reaction to external conditions and play a role in how tired one feels.

What chemical changes are seen?


These chemical changes involve ultraviolet rays from the sun. When these rays hit the body, it’s important to find shade and not remain exposed for longer periods. Most people run from these rays due to cancer development or feeling hot, but there is more to it. The idea is to not only find shade but to fight back by drinking water or eating salty snacks. This is the only way to stay healthy.

Remember, the body is going to be sweating as it adapts and this means fluids are lost. When those fluids are lost, the body starts to slow down. It is a natural chemical change where balance isn’t maintained and the body has to compensate by slowing down.

If not, there will come a time when the body shuts down, and that’s what happens to those who are heavily exposed in the desert.

Remaining aware of these chemical changes is important.


These are the reasons heat can make you tired, and it’s best to prepare for this. People who find it difficult to sleep at night should be looking at improving the temperature in their room. The same applies to those who spend a long day at the beach. You want to stay prepared and make sure you’re consuming enough water and taking the time to appreciate what’s going on.

As long as you adapt, the body will be okay.

Most people don’t realize that the heat leads to fatigue and that’s where problems begin. For those who want to remain full of energy, this is a good starting point and will help you in the long-term.

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