Summer and Psyche: How heat affects your brain

Heat has a negative effect on the psyche. High temperatures lead to poorer cognitive performance, for example, but also promote various mental illnesses.

Do you often feel like you have a harder time concentrating and that everything is generally more difficult on particularly hot days? You’re not alone!

Various studies show that heat can have a strong impact on our psyche. During heat waves, for example, our mental performance decreases. In addition, the stress that occurs as a result of the high temperatures can cause depression and anxiety disorders or worsen existing symptoms.

Heat and Psyche: Declining Cognitive Abilities

There is now a wide range of scientific evidence for the connection between heat and mental health. According to Psychology Today, they all come to the same conclusion: high temperatures have a negative effect on cognitive abilities.

For example, a 2024 study from China examined how heat affected the ability of test subjects to solve mathematical problems. The researchers found that test results were significantly worse at temperatures above 32 degrees Celsius than at temperatures of 22 to 24 degrees.

In addition, the strongest effects occurred in people who were not used to the heat. In people who already lived in warmer areas, however, the heat had less of an effect on the test results. They were already better adapted to the high temperatures.

A 2019 review concluded that soldiers were less able to perform complex cognitive tasks when exposed to heat stress. This effect was exacerbated when participants had to engage in physical activity in hot weather.

According to the AOK, the fact that we are less cognitively capable in hot weather is probably because the body generally uses more energy at high temperatures. Accordingly, there is less energy left for the brain. This is particularly the case when we are exposed to heat at night and cannot cool down properly even when we are sleeping.

Heat and Psyche: Depression and Anxiety Disorders

According to the Medical University of Vienna, prolonged periods of heat can promote depression and anxiety disorders, as well as alcohol and substance use. People who already suffer from a mental illness often experience worsening symptoms in hot weather. In addition, an increase in average temperature is also associated with a higher suicide rate.

Environmental physician Hans-Peter Hutter from the Medical University of Vienna is therefore urging us to take a closer look at the psychological consequences of the climate crisis. There is a fear that as the number of hot days per year increases, mental illnesses and suicides will also increase.

In addition, the potential for aggression increases in hot weather, meaning that more violent crimes occur during heat waves. At the same time, heat can also have a dampening effect on the psyche, which can manifest itself in a depressed mood or apathy.

Depression in summer: cortisol and melatonin

One possible reason for the connection between heat and mental health could be a feeling of climate anxiety. As the heat increases, people may get a feeling of helplessness, which, according to Hutter, in turn causes the body to release higher amounts of the stress hormone cortisol. Over a longer period of time, this stress hormone promotes various physical and mental complaints, such as depression.

According to the AOK, however, it could also be a so-called summer depression. This is not directly related to the heat, but to the sleep hormone melatonin. Melatonin is responsible for the sleep-wake rhythm and is mainly released in the dark. In summer, the body produces less melatonin. This could promote seasonal depression. However, further scientific research is needed in this area to better understand the connections.