Heat is not something you endure with sheer willpower: Damage to the heart, kidneys, and brain

1) "It's hot..." is a sign that your body is desperately trying to "cool down."

The summer heat begins with a "slightly sweaty" feeling. You use a fan, loosen your collar, and drink water. However, as the temperature rises further, a "different battle" begins within your body.

Our bodies try to maintain a nearly constant internal temperature (about 36.5°C) regardless of the outside temperature.InfoMoney

If this "homeostasis" is disrupted, enzyme reactions and organ functions become disordered, and in the worst case, it can be life-threatening. In other words, extreme heat is not just uncomfortable; it is a stress that directly hits the basic functions of the body.

2) Body's Cooling System: Vasodilation and Sweating are a "Set"

When exposed to heat, the body releases heat mainly in two ways.

• Vasodilation of skin blood vessels: Carries heat from the body's core to the skin surface and dissipates it outside.

• Sweating: When sweat evaporates, it takes away heat and cools the body surface.

As long as this mechanism is working well, you can endure some heat.
However, there is a pitfall here.

• High humidity → Sweat doesn't evaporate easily, and cooling doesn't occur.

• Lack of fluids → Unable to sweat, cooling stops.

• Prolonged heat → The burden on the circulatory system (heart and blood vessels) accumulates.

As a result, symptoms such as "shortness of breath," "dizziness," and "feeling dazed" are more likely to occur. Feeling suddenly uncomfortable on a crowded bus or during outdoor work is not due to a lack of effort, but because your cooling system is nearing its limit.InfoMoney

3) Heatwaves are a "Silent Disaster"—Actually the Most Lethal Extreme Weather

Unlike floods or typhoons, heatwaves cause less visible destruction but have a significant impact on health. The World Health Organization (WHO) has introduced research indicating that approximately 489,000 people worldwide died annually from heat-related causes between 2000 and 2019.World Health Organization

Moreover, extreme heat is not only linked to "heatstroke" but can be life-threatening through multiple conditions. Research has shown that heatwaves can become lethal through at least 27 physiological pathways.PubMed

4) What Gets Affected? "Chain Reactions Caused by Heat" by Organ

The original article highlights areas prone to heat-triggered issues, including cardiovascular, respiratory, cerebrovascular, renal, and metabolic (diabetes) systems.InfoMoney

The key point is that it doesn't end with "heat → sweat"; circulation, inflammation, and cellular damage can chain-react.

Heart and Blood Vessels: The Heart Becomes "Overworked"

When the skin blood vessels dilate due to heat, the heart needs to work faster and stronger to maintain blood pressure. For those with pre-existing heart or vascular conditions, the imbalance with oxygen supply increases the risk of ischemia and myocardial infarction.InfoMoney

Respiratory System: Worsens with Heat Stress and Immune Response

The immune response to stress and cellular damage caused by heat also burdens the respiratory system, making existing respiratory diseases more likely to worsen.InfoMoney

Brain: Increased Risk Due to Blood Flow Changes and Barrier Disruption

The original article points out the impact on blood flow to the brain and the blood-brain barrier, which in severe cases can lead to ischemic or hemorrhagic issues.InfoMoney

Kidneys: Increased Danger from Dehydration × Heat Stress × Work Environment

Kidneys are susceptible to dehydration, and when combined with heat stress, the damage increases. For those occupationally exposed to heat, kidney damage risk is a significant concern. A review indicates that kidney disease and acute kidney injury are observed in about 15% of people working in hot environments.The Lancet

Sleep and Mental Health: Heat That Prevents Sleep "Reduces Concentration"

The original article points out that heat lowers sleep quality, affecting mood, attention, and motivation, which can lead to judgment errors and accidents.InfoMoney
"Lack of sleep + dehydration + scorching heat" weakens not only physical strength but also decision-making.

5) "Who is at Risk?"—Not Just the Elderly: "Weaknesses to Heat"

The original article lists groups more susceptible to heat, including the elderly, children, obese individuals, those with diabetes, heart disease, respiratory diseases, and kidney diseases.InfoMoney

Additionally, it is generally suggested that women may have lower heat tolerance due to factors like body fat distribution and hormones.InfoMoney

The important point here is the tendency to think, "I'm healthy, so I'm fine."
In reality, lack of sleep, alcohol consumption, hangovers, diarrhea, excessive intake of diuretic beverages, and prolonged outdoor activities can make anyone suddenly vulnerable depending on their condition.

6) Common Reactions on Social Media: "I Know, But I Can't Help It" and "Air Conditioner Guilt"

During the hot season, the following "common" reactions increase on social media.
※ The following are not specific posts but examples that recreate the trend of reactions repeated every year.

• "I'm drinking water, but I feel dazed. Is this dehydration?"

• "It's only 10 minutes to the station, but my heart is pounding. Was summer always this tough?"

• "My child can't sleep and is in a terrible mood. The parents are at their limit too."

• "Afraid of the air conditioning bill vs. afraid for my life if I don't use it."

• "On days I work outside, three bottles of water aren't enough."

• "It's so hot I lose my judgment. I went shopping and forgot what to buy."

• "Lack of sleep + heat leads to work mistakes. Summer productivity has melted away."

These voices make sense when viewed from the body's mechanism.
Heat overworks the circulatory system to maintain body temperature, disrupts sleep, reduces concentration, and accelerates dehydration. As a result, "feeling exhausted," "making mistakes," and "getting irritated" occur simultaneously.InfoMoney

7) "Mosquitoes and Ticks" Also Increase—Heat Raises "Infectious Disease Risk"

The impact of heat is not limited to the body. Rising temperatures also affect the activity and habitat of vectors like mosquitoes and ticks.
The CDC explains that climate can be a risk factor for vector-borne diseases.CDC

The WHO also organizes heat risks from a climate and health perspective, showing that heatwaves are a major public health issue.World Health Organization

Regarding dengue fever, the WHO has warned of increased infection risks due to global warming and other factors.Reuters

8) Practical Measures You Can Start Today to "Stop Before Breaking from the Heat"

The original article also recommends measures like **adequate hydration, light clothing, and cold water compresses (cooling)**.InfoMoney
Here, we summarize them in an easy-to-implement form.

① Hydrate "Frequently and in Advance"
Drink before you feel thirsty. On sweaty days, consider electrolytes in addition to water, depending on the situation.

② Dress in a "Heat-Dispersing Design"
Choose clothing that allows airflow, absorbs sweat quickly, and isn't tight. All-black or thick clothing tends to trap heat.

③ Target "Neck, Armpits, Groin" for Cooling
Applying a cold towel or ice pack to these areas can increase efficiency.##HTML