Unusual fatigue, a feeling of suffocation, difficulty concentrating, disturbed sleep... When a heatwave sets in, we don't all react in the same way.
Some people continue their activities almost normally despite high temperatures. Others quickly feel the need to slow down, seek shade, or stay indoors during the hottest hours.
This difference is not just about perception. It is explained by a combination of factors related to our body, our environment, and our lifestyle.
As episodes of intense heat become more frequent in many parts of Europe, understanding these mechanisms also helps us adapt better to daily life.
At Quello, we are particularly interested in this relationship between the body and its environment: sun, heat, wind, cold, sleep, or scalp comfort often influence our well-being more than we imagine. This reflection led us to explore the effects of intense urban heat in our article How to better live through a heatwave in the city?
Why do some people tolerate heat less well?
The human body has very effective mechanisms for maintaining its internal temperature around 37 °C.
When the air heats up, blood vessels dilate, and perspiration increases to evacuate excess heat. This adaptive capacity allows us to withstand significant temperature variations.
But this regulation requires energy.
The more intense or prolonged the heat, the more the body has to work to maintain its balance. This constant demand explains why some people experience significant fatigue even without particular physical activity.
Heat therefore does not only affect our feeling of comfort: it truly mobilizes the body's resources.
Age strongly influences tolerance to high
heat
Age is one of the best-documented factors.
Older people often experience a decrease in the sensation of thirst and a reduced ability to dissipate heat through perspiration. They are therefore more exposed to the effects of high temperatures.
Young children are also more sensitive to heatwave episodes, as their thermoregulation mechanisms are not yet fully mature.
Between these two extremes, each individual has their own adaptive capacity.
General health status, certain medical treatments, or even the level of physical activity can alter how the body reacts to heat.
Sleep, stress, and fatigue can accentuate the feeling of heat
Heat is not just a matter of external temperature.
Our general state also plays an important role.
After several disturbed nights or a period of prolonged stress, many people find that intense heat becomes more difficult to bear.
Lack of sleep reduces the body's recovery capacities. Stress, for its part, already increases certain physiological demands.
When heat is added to this fragile balance, the feeling of exhaustion can appear much more quickly.
This reality explains why two people exposed to the same temperatures can experience very different levels of discomfort.
Why is heat often harder to bear in the city?
Not all heat is the same.
A temperature of 30 °C in a natural and ventilated environment does not produce the same sensations as 30 °C in the heart of a large city.
Buildings, stone, concrete, and asphalt absorb solar energy throughout the day and then gradually release it during the evening and night.
This phenomenon is known as the urban heat island effect.
In many European cities, this accumulation of heat reduces the body's ability to recover at night and contributes to a more lasting feeling of discomfort. This is notably what makes some urban heatwaves particularly trying. The sun itself also contributes to this fatigue, a phenomenon we explore in more detail in our article Why the sun makes you tire more than you think — and the forgotten role of the head.
Hair and scalp also contribute to thermal comfort
When it's very hot, we naturally think of protecting our skin or drinking more water.
However, hair and scalp also contribute to daily comfort.
Direct sun exposure, perspiration, or even heat accumulation around the head can accentuate certain feelings of discomfort.
Hair sticking to the neck, oilier roots, a sensitive scalp, or a feeling of overheating are frequently observed phenomena during hot periods.
This is notably why many people look for lightweight caps that create a shaded area on the face and scalp or prefer comfortable headbands that hold hair while allowing air to circulate.
This protection is often more important than we imagine, as we explain in our article Why protecting your head is more important than you think.
How to better cope with high heat daily?
There is no universal solution.
However, several simple adjustments often help improve comfort during hot periods.
Preserving sleep when possible, seeking shaded areas, adapting your rhythm to the coolest hours of the day, and maintaining regular hydration are among the most common recommendations.
The choice of materials can also influence felt comfort. Lightweight and breathable fabrics generally promote better air circulation.
We will soon address this topic in more detail in an article dedicated to the most suitable materials for high heat.
Live summer better rather than fight it
We are not all equal when it comes to high heat.
Age, sleep, health status, the urban environment, and our level of fatigue profoundly influence how we perceive high temperatures.
Understanding these differences often allows for a more nuanced perspective on one's own feelings.
If some summer days seem particularly trying, it doesn't necessarily mean you lack resilience. Your body is simply reacting to its own specific constraints.
Sometimes, finding a bit of comfort comes from modest adjustments: more shade, a slower pace, lighter materials, or an accessory adapted to your environment.
After all, summer is not just a season to endure. It is also a season to inhabit.
Sources and references
The information presented in this article is based on works dedicated to human thermoregulation, the health effects of heatwaves, and urban thermal comfort.
- World Health Organization (WHO) – Heat and Health
- European Environment Agency (EEA) – Climate change, impacts and vulnerability in Europe
- Guyton & Hall – Textbook of Medical Physiology
- International Journal of Biometeorology – research on urban thermal comfort
- Météo-France – Understanding heatwave episodes and their effects on the body