After spending some time outdoors on hot summer days, we often begin to feel tired, weak, and sleepy. But why does heat affect us this way?
According to experts, the reason is simple: our bodies have to work harder than usual to stay cool, and this extra effort leads to fatigue.
Dr. Michele Casey, Regional Medical Director at Duke Health in North Carolina, explains that the body works intensively to maintain a stable and normal internal temperature, especially when exposed to direct sunlight.
In hot weather, the body undergoes several changes to regulate its temperature. One of these is the widening of blood vessels. This process, known as vasodilation, increases blood flow to the skin. As warm blood moves closer to the surface of the skin, it releases heat into the surrounding environment and cools down.
This is why people often appear flushed or red in hot weather.
The body does not rely solely on dilating blood vessels. It also produces more sweat on the skin's surface. As sweat evaporates, it helps cool the body.
However, all of these processes require additional energy. The heart beats faster, the metabolic rate increases, and the body burns more calories.
Dr. Casey notes:
“All of this extra activity—an increased heart rate and a higher metabolic rate—ultimately makes a person feel tired and sleepy.”
In addition, most people do not drink enough water throughout the day and remain mildly dehydrated. Hot weather and excessive sweating only worsen this condition. One of the main symptoms of dehydration is fatigue.
Sun exposure can make the situation even more difficult. Ultraviolet rays from the sun can cause changes in skin pigmentation, wrinkles, and sunburn.
Dr. Casey explains:
“These chemical changes also contribute to fatigue because the body has to expend additional energy repairing the damage.”
Sunburn can also impair the body's ability to regulate its temperature. Moreover, the body uses more fluids to heal damaged skin. This leaves less fluid available for sweating, which further increases dehydration and fatigue.
How can you protect yourself in the heat?
Many people try to cool down by drinking alcoholic beverages. However, alcohol acts as a diuretic and can worsen dehydration.
According to recent studies, coffee does not have as strong a diuretic effect as previously believed. Nevertheless, the best way to fight dehydration is to drink plenty of water.
Experts also recommend consuming salty snacks along with water, such as pretzels or baked potato chips.
Doctors advise people to watch for the main signs of heat exhaustion:
• Heavy sweating
• Rapid pulse
• Weakness
• Dizziness
• Feeling sleepy
If these symptoms occur, it is recommended to move to a cool place immediately, drink water, and seek medical attention if the condition does not improve within an hour.
Heat stroke is a more serious condition
During heat stroke, the body's core temperature rises to a dangerously high level. This condition requires emergency medical treatment because it can seriously damage the brain, heart, kidneys, and muscles.
The main symptoms of heat stroke include:
• High body temperature
• Nausea and vomiting
• Severe headache
• Confusion and difficulty concentrating
• Behavioral changes, agitation, and irritability
• Speech problems
• Seizures
• Even coma
Experts recommend staying in the shade or in air-conditioned environments, avoiding prolonged exposure to direct sunlight, especially during the hottest hours of the day, and drinking enough water throughout the day.
Sometimes the reason we feel exhausted is not simply the hot weather itself. In reality, our bodies are constantly working to keep us cool, and this invisible effort consumes energy and leaves us feeling tired.