What are the effects of heat on our brain?

Summer has already reached extreme temperatures. With heat records seemingly destined to be broken year after year, the health risks also affect our brain, an organ that is particularly susceptible to fluctuations in temperature. What happens to our brain when temperatures rise, what are the consequences for our cognitive abilities and mental healthAccording to the World Health Organization, mental health ca... More? Which groups are most at risk, and are there any ways to protect ourselves?

How Heat Disrupts Brain Function

Summer 2026: Increase in Emergency Department Visits

The extreme heat of summer 2026 has led to an increase in visits to some Emergency Departments for psychiatric disorders, according to a statement from SIMEU (Italian Society of Emergency Medicine and Surgery) and SIEP (Italian Society of Psychiatric Epidemiology). The statement highlights how excessive heat can exacerbate symptoms of anxietyAnxiety is an emotional response characterized by feelings o... More, depressionDepression is a disorder characterized by persistent sadness... More, mood disorders, and psychiatric conditions.

Temperature and the Brain

The brain has an optimal temperature that is, on average, higher than that of the rest of the human body (37°C). Its average temperature actually reaches 38.5°C, with the innermost regions approaching 40°C. The brain is a highly complex machine, and even minimal temperature variations can disrupt the delicate chemical balance between the different components involved.

An experiment conducted by Yale University showed that neurons stimulated using Deep Brain Stimulation had reduced functionality. This technique delivers energy to the gray matter through electrodes, causing a rise in temperature, with effects that can be felt even after an increase of just one degree. The change would in fact affect the molecular pumps on neuronal membranes, compromising the proper use of neurotransmitters. This effect disappears only after the neuron has had time to cool down and return to its initial state.

Electrolyte Loss and Vasodilation

In addition to neurotransmitters, heat can also disrupt the levels of electrolytes needed by our brain for neural activity, which we lose through excessive sweating. Humid heat can lead to breathing difficulties and shortness of breathBreathing is a natural and physiological process that suppli... More, resulting in a reduced supply of oxygen to the entire body, including the brain. Heat also increases blood flow to the brain, dilating blood vessels and causing headaches, migraines and, in more severe cases, an inflammatory response. In short, an overheated brain is a stressed brain.

Risks and Consequences of Heat on the Brain

The consequences of this brain stressFrom a clinical point of view, stress is a physiological and... More can be both cognitive and emotional. It is no coincidence that, statistically, school tests taken on the hottest days tend to produce worse results. A study conducted by Harvard University compared two groups of students living in a dormitory: the first slept in rooms with air conditioning set to 21°C, while the second slept in rooms without air conditioning, where the average temperature was 27°C. After 12 days, researchers found a significant decline in academic performance and in cognitive association tests among the second group. Once temperatures exceed 27 degrees, our ability to concentrate drops dramatically.

Heat Takes a Toll on Our Mood

Mood is also affected: irritability, anxiety, aggression, and lack of motivationMotivation: a scientific perspective Motivation is a fundame... More can set in. In addition, the brain mechanisms responsible for helping us relax cannot function efficiently because they are too busy compensating for the thermal imbalance. In the long run, these effects can exacerbate underlying mental health conditions. Several studies have found a link between heat waves and an increase in hospital admissions related to depression, schizophrenia, and substance abuse.

The Danger of Heatstroke

These heat waves can also cause more serious and potentially life-threatening risks, including a state of confusion, fainting, or the proverbial heatstroke. When body temperature reaches 40°C, the blood-brain barrier, which separates brain tissue from the bloodstream, stops functioning properly. Bacteria and harmful particles that were previously kept separate are free to circulate through brain tissue, triggering an inflammatory response that, over time, can cause permanent damage.

At these temperatures, proteins denature and cell death can also occur, primarily affecting cells in the cerebellumThe cerebellum is a structure composed of two symmetrical ce... More, the area responsible for balance and movement coordination. For this reason, heatstroke is considered extremely dangerous, especially for older people.

Climate Change and Brain Health

Unfortunately, heat-related problems are destined to increase: with climate change and the resulting global warming, our brains will be increasingly exposed to these risks. Statistics show an increase in the number of hospital admissions and deaths caused by heat in recent years, corresponding to the rise in temperatures. A study by Imperial College London and the London School of Hygiene & Tropical Medicine reports that the number of deaths linked to heat waves had already tripled by 2025.

Climate Anxiety

Not only that, but pollution and environmental disasters such as floods, wildfires, and droughts also affect brain health, both directly and indirectly. Climate anxiety, particularly prevalent among adolescents, is a psychological response to the challenges and uncertainties of the future world and contributes to a widespread decline in mental health.

However, it can also become a driving force for action: it is precisely through active engagement in climate action that younger generations are finding a way to maintain hope, forge connections, and build shared projects.

3 Tips to Protect Our Brain from the Heat

In the meantime, we can continue to protect our brains from the heat with a few simple tips:

1. stay out of direct sunlight
2. rest as much as possible in cool places
3. drink plenty of water.

For those taking medication or undergoing psychological treatment, it is advisable to consult their specialist about the additional risks posed by heat and any further health precautions.