By Geradine Ohonba
Health Editor/Columnist
As global temperatures continue to rise due to climate change, extreme heat events are becoming more frequent, intense, and prolonged. While heatwaves are often discussed in terms of their visible effects — scorched landscapes, overloaded power grids, or public health warnings — the invisible impact on our physical and mental health is just as alarming. Heat stress doesn’t just make us uncomfortable; it can compromise our body’s most basic functions and quietly affect our cognitive and emotional well-being.
Understanding Heat Stress
Heat stress occurs when the body is unable to cool itself effectively, usually due to prolonged exposure to high temperatures, high humidity, or intense physical activity in hot conditions. The human body tries to maintain a stable internal temperature, usually around 98.6°F (37°C), but excessive heat can overwhelm this balance.
The body reacts to heat stress by sweating, increasing blood flow to the skin, and raising heart rate. When these mechanisms fail — especially when hydration is inadequate or cooling options are limited — the results can range from mild dehydration to life-threatening conditions like heat exhaustion and heatstroke.
Physical Consequences of Heat Stress
1. Dehydration
High heat leads to increased sweating, which causes fluid and electrolyte loss. Without proper replenishment, this leads to dehydration, resulting in fatigue, dizziness, and reduced physical performance.
2. Heat Exhaustion
This condition includes symptoms like nausea, headache, muscle cramps, and confusion. It’s the body’s signal that it’s struggling to cope with the heat.
3. Heatstroke
A medical emergency, heatstroke occurs when body temperature rises above 104°F (40°C). It can result in seizures, loss of consciousness, and even death if not treated immediately.
4. Cardiovascular Strain
The heart has to work harder to pump blood to the skin for cooling. This increased cardiovascular load can be particularly dangerous for people with preexisting heart conditions.
5. Kidney Problems
Chronic exposure to heat and repeated dehydration can increase the risk of kidney stones and long-term kidney damage, especially among outdoor workers and athletes.
6. Impaired Immune Response
Ongoing heat stress may weaken the immune system, making the body more susceptible to infections and slower to heal.
Mental and Cognitive Impacts of Heat
Less widely recognized — but just as serious — are the psychological and neurological effects of heat stress. High temperatures can affect the brain’s ability to function optimally.
1. Reduced Cognitive Performance
Studies show that excessive heat can slow reaction times, reduce focus, and impair memory. This is especially dangerous in high-stakes professions like driving, construction, or operating machinery.
2. Increased Irritability and Aggression
Heat alters the brain’s serotonin and dopamine balance, contributing to mood swings, frustration, and even aggressive behavior. Crime rates and incidents of violence often rise during heatwaves, partially due to these neurochemical changes.
3. Exacerbation of Mental Illness
People with existing mental health disorders, such as anxiety, depression, or schizophrenia, may experience worsening symptoms. Medications like antipsychotics and antidepressants can also interfere with thermoregulation, making these individuals more vulnerable to heat-related illnesses.
4. Sleep Disruption
Hot temperatures — especially at night — interfere with the body’s ability to cool down for sleep. Poor sleep quality leads to fatigue, reduced alertness, and emotional instability, further amplifying mental health issues.
5. Heat-Related Anxiety
Just as some people experience seasonal depression in winter, others may suffer from heat-induced anxiety or distress. Prolonged heatwaves can create a sense of helplessness or dread, especially among those without access to cooling resources.
At-Risk Populations
Certain groups are especially susceptible to the effects of heat stress on both body and mind:
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Elderly individuals, due to impaired thermoregulation
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Children, whose bodies heat up faster and cool down more slowly
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Outdoor workers and athletes, due to increased physical exertion in heat
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Low-income households, who may lack access to air conditioning or safe cooling centers
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People with chronic illnesses such as diabetes, cardiovascular disease, and mental health disorders
Preventing and Managing Heat Stress
Preventing heat-related health issues requires both personal strategies and community-level interventions:
Personal Safety Tips:
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Stay hydrated and drink water regularly, even if you don’t feel thirsty.
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Wear loose, light-colored clothing and a hat when outdoors.
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Avoid strenuous activity during the hottest part of the day (usually 12–4 PM).
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Use fans, air conditioning, or visit public cooling centers if available.
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Take cool showers or use wet cloths on pulse points (neck, wrists, ankles).
Community and Policy Solutions:
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Governments should issue early heat warnings and establish accessible cooling shelters.
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Urban planning can mitigate heat stress with green spaces, shaded areas, and reflective building materials.
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Workplaces should implement heat safety protocols, including scheduled breaks, shaded rest areas, and access to water.
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Schools, hospitals, and elderly care homes must ensure indoor cooling systems are functional and well-maintained.
Heat Is More Than Just a Number
Heat stress is a silent but deadly threat, affecting not just the body but also the mind. As climate change accelerates, communities and individuals must begin to treat heat as a serious public health hazard, not just an inconvenience. Understanding the full scope of heat’s impact empowers us to take preventive action and protect the most vulnerable among us.
In a warming world, resilience begins with awareness, preparation, and compassion — for our own well-being and for those who may struggle silently in the heat.
