According to a recent communiqué on the official website of the European Union’s climate monitoring agency, the Copernicus Climate Change Service (C3S), the global daily average temperature has broken the highest single-day record for the second consecutive day. High temperatures are becoming a global problem. The World Meteorological Organization issued a press release in January this year, officially confirming that 2023 will be the hottest year on record.
Australia's "Conversation" magazine reported that in 2024, many countries in the Americas, Africa, Europe and Asia experienced record high temperatures. In Mexico and Central America, weeks of high temperatures and prolonged drought that began this spring have led to severe water shortages and dozens of deaths. Spanish newspaper El Pais reported that the first wave of heat waves this summer has put 80% of Spanish urban residents at risk to their health.
It is worth noting that high temperatures not only cause health problems such as dehydration, but also affect the brain, an organ that is extremely sensitive to temperature.
Academic performance and work efficiency have declined
"Extreme heat affects all cognitive functions of the brain, including reflexes, memory, etc. At high temperatures, the brain operates much more slowly," explains Sandra Jimenez, a clinical neurophysiologist at the Hospital de Sant Croix de São Paulo in Spain.
Scientific evidence also supports this idea. A study conducted in New York public schools in the United States in 2018 showed that taking a test when the temperature is higher than 32℃ will lower your score by 14% and the probability of passing the test will be reduced by nearly 11% compared with taking the test in a weather of 22℃.
Another study conducted in the United States reported that learning efficiency decreases with rising temperatures. The study compared the performance of Boston University students during the 2016 heat wave and found that students in rooms without air conditioning (average temperature was 27 degrees Celsius) had 13 percent slower reaction times on arithmetic tests and nearly 10 percent less accuracy on arithmetic tests than their air-conditioned classmates (average temperature was 22 degrees Celsius).
Cognitive decline caused by extreme heat can also impact workplace performance. A study conducted in 2006 found that productivity was highest at temperatures around 22°C. And when the temperature is 8℃ higher, productivity levels will decrease by nearly 9%.
Rising temperatures increase negative emotions
Spanish meteorologist and science popularization expert Mar Gomez said that research shows that high temperatures can easily lead to mental health problems. She notes that rising temperatures reduce positive emotions such as joy or happiness while increasing negative emotions such as anger or stress.
"People with schizophrenia may have difficulty regulating their body temperature, and changes in temperature can alter the symptoms of mood disorders. Additionally, some psychiatric medications, including certain antidepressants and antipsychotics, can affect the way the body regulates body temperature, and people taking these medications are susceptible to the effects of extreme heat," Gomez explains.
Among the negative emotions associated with heat, anger is one of the most studied. Two of its direct consequences - aggression and violent behavior - are also the focus of research. Extreme heat can increase a person's irritability and reduce self-control, which can lead to more aggressive behavior.
A study published in The Lancet in 2022 analyzed 4 billion Twitter messages and found that extremely high or low temperatures can promote aggressive trends online and increase hate speech. On days with extremely hot weather (42°C to 45°C), the increase in this type of Twitter is as high as 22%.
High temperatures force the brain to work harder to regulate body temperature
The reason for all these consequences is that "high temperatures force the brain to work harder to regulate its body temperature, thus negatively affecting it," according to Valentin Martinez, a PhD in psychology at the Universidad Complutense of Madrid and a member of the School of Psychology of Madrid.
Gomez explains that the brain functions properly thanks to the hypothalamus. It is the coordinator of the autonomic nervous system and acts as the brain's internal thermostat. When the hypothalamus detects a difference between its own temperature and that of the skin's thermoreceptors, it sets up regulatory mechanisms: from sweating to dilation of blood vessels to the secretion of adrenaline, one of the reasons why people become more irritable in hot environments.
Gimenez, coordinator of the cognitive and sleep working group of the Spanish Sleep Association, said high temperatures can lead to a vicious cycle. Sleep quality deteriorates, resulting in cognitive decline and people becoming more anxious and irritable, symptoms that are exacerbated by daytime heat.
"The control of the prefrontal lobe of the brain is weakened, and the 'braking' effect of the amygdala, which is responsible for processing emotions, is weakened, so that all negative emotions are amplified." She explained.
Facing the hot summer, people are not helpless. Martinez offers several suggestions, such as drinking plenty of water to stay hydrated; avoiding prolonged exposure to extreme heat, especially at noon; finding cool, air-conditioned areas; wearing light, light-colored clothing to facilitate perspiration; limiting strenuous outdoor activities during the hottest times of the day; eating light, water-rich foods such as fruits and vegetables; and doing everything possible to get enough sleep.