When the human body is exposed to heat, it constantly works to keep its core temperature within a safe range. This balance is maintained through sweating, increased skin blood flow, and changes in heart rate. When heat exposure becomes too intense or lasts too long, these systems struggle to keep up. As a result, body temperature rises, placing stress on the heart, brain, and other organs. This is why staying cool is not only about comfort, but about basic physiological safety.

From a health perspective, heat stress can quickly reduce physical and mental performance. Research on workplace and environmental heat exposure shows that work capacity drops sharply when temperatures exceed safe limits, especially when humidity is high. The Wet Bulb Globe Temperature (WBGT), a common heat index, demonstrates that once values rise above roughly 26–30°C, the body needs frequent rest to avoid overheating.

Without cooling breaks, core body temperature can rise above 38°C, increasing the risk of heat exhaustion and heat stroke. Older adults, people with chronic illness, and those performing physical work are particularly vulnerable.

Heat also affects the brain. Reviews of laboratory and real-world studies show that hot environments reduce attention, reaction speed, and complex thinking, even when people feel only moderately uncomfortable. Simple tasks may remain unaffected, but decision-making, memory, and sustained focus tend to suffer as body temperature increases.

Meta-analyses suggest that cognitive performance can drop by more than 10% in hot conditions compared to neutral temperatures. Over longer periods, heat exposure has also been linked to higher mortality rates, with population studies showing a 1–3% increase in death risk for each degree rise above local heat thresholds.

Effective cooling strategies focus on reducing heat load and supporting the body’s natural cooling systems. Drinking fluids, reducing physical effort during peak heat, using shade and airflow, and wearing breathable clothing all help stabilize body temperature.

In contrast, ignoring thirst, wearing heavy clothing, or pushing through heat without rest increases strain and risk. Overheating is rarely sudden; it builds gradually, making early cooling actions critical for preventing serious outcomes.