Article by GSP – Published on Tuesday, 14 April 2026, 14:59 / Updated on Tuesday, 14 April 2026 14:59
When the thermometer shows 37 degrees we tend to react more aggressively than usual. We get angry in traffic and at home, banal discussions can degenerate into fights of proportions.
Why do we get grumpy when it's very hot? Here's what the science says.
Heat puts the body on alert and that drains our energy
During the heatwave, the body automatically enters a state of heat stress. Energy resources are redirected to a single goal: maintaining the internal temperature at 37 degrees. When it's 38 outside, this is much more difficult.
The body responds to this stress by releasing more cortisol, a hormone essential for adaptation, but which, in excess, maintains a state of alertness and lowers tolerance for frustration. Basically, the body thinks it's facing imminent danger, and that lowers our tolerance for frustration. This is where impulsive reactions, irritability and the tendency to interpret ordinary situations more negatively arise.
In addition to cortisol, heat also triggers an increased production of adrenaline, the hormone responsible for the “fight or flight” response, which amplifies emotional reactivity in difficult situations.
A air conditioning chosen correctly can reduce the ambient temperature and keep it at a comfortable level, which does more for your emotional state in the heat than any relaxation technique. This is the first measure to help the body get out of the alert state, but done gradually. The sudden change from very hot to very cold can create additional stress on the body.
It is ideal to gradually lower the temperature, constantly hydrate and avoid prolonged exposure to extreme heat. Thus, you help the body to come out of the alert state and regain its natural balance.
At 38 degrees, your brain has less control over your reactions
The part of the brain responsible for self-control and decision-making, the prefrontal cortex, needs energy to function properly. But in the heat, much of this energy is already consumed by body temperature regulation processes, which reduces our ability to filter impulses, like after a sleepless night.
The area of the brain responsible for regulating body temperature, the hypothalamus, also plays a role in controlling emotions. When the body is struggling to regulate temperature, the two brain functions are fighting for the same energy resources, and emotional regulation is at a loss, not being essential for survival.
Dehydration amplifies this vulnerability. Even a slight deficit disrupts the synthesis of serotonin, the neurotransmitter associated with emotional balance, and this makes us more reactive to stress. Also, fragmented sleep on hot nights aggravates the condition of the amygdala, which makes us more irritable.
The effects are cumulative. Prolonged exposure to high temperatures, combined with lack of rest, leads to a progressive decrease in stress tolerance and potentiates irritability from day to day.
All of these factors reinforce each other: elevated cortisol, lack of energy, dehydration, and chemical imbalances create a cocktail that amplifies irritability. Basically, the psychological reaction is due to a complex physiological response in which the body tries to cope with thermal overload.
Irritability during heatwave – a documented collective reflex
Irritability during heatwave is a collective reflex, well documented scientifically. Studies show that during periods of high temperatures, the frequency of aggressive behaviors increases. For example, researchers at Iowa State University observed a roughly 2.6 percent increase in aggressive incidents during the summer months compared to the rest of the year.
One of the clearest experiments on this topic was carried out in Arizona in the 1980s. The researchers analyzed the behavior of drivers stopped at traffic lights. The results showed that as the temperature increased, the duration and intensity of the honking increased. Interestingly, this effect disappeared in air-conditioned vehicles, where the ambient temperature was more comfortable.
Thermal discomfort influences our behavior more than we think. So the next time someone honks, maybe they're not mad at you. Maybe he's just too hot.
How to reduce irritability when temperatures rise
Understanding the science behind irritability is important, but it doesn't lower our body temperature. Specialists recommend simple but effective interventions that can reduce thermal stress on the body:
First of all, the ambient temperature must be lowered. Whether you turn on the air conditioner at home or in the car, set the temperature gradually to avoid thermal shocks – these can give cold symptoms. You can use a fan as well. It is also important to keep the space where you are sitting shaded and avoid direct exposure to the sun during peak hours.
Proper hydration is equally important for regulating cognitive and emotional functions. Drink 2.5 liters of water a day in the summer, possibly 1-2 glasses every hour, even if you are not thirsty: by the time you feel thirsty, the brain is already in deficit. This will help prevent fatigue and support your ability to concentrate. If you sweat a lot, you also need electrolytes.
Last but not least, you need quality restful sleep to manage your emotions and not become too irritable during the heatwave. Maintain a regular sleep schedule of at least 8 hours and create a cooler environment at night using the Sleep mode of the air conditioner.
