Feeling overheated physically? Remember to cool down your mind, too.

It's been so hot lately that air conditioners, fans, watermelons, and mung bean soup have all come to the rescue. But don't forget to cool down your mind while cooling down your body, because the impact of high temperatures on your mind cannot be ignored.

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01 When the temperature exceeds 21℃, does happiness begin to decline?

Studies have shown that temperature changes can affect mental health. Both extremely high and extremely low temperatures can have a negative impact on an individual’s mental health, as evidenced by an inverted U-shaped correlation between temperature and mental health[1].

A follow-up survey in the United States involving 1.9 million samples showed that between 2008 and 2013, compared with the average temperature (10-16°C), temperatures above 21°C reduced positive emotions and happiness, increased negative emotions such as stress and anger, and caused people to experience fatigue and powerlessness[2]. This result is also supported by other studies. For example, a 2019 study found that when the temperature exceeded 21°C, an individual's sense of happiness would decrease, while when the temperature exceeded 32°C, an individual's stress, fatigue and negative emotions would increase significantly[3].

More and more studies have shown that when the temperature is too high, people may experience psychological feelings such as depression, anger, and pain, which in turn affects their mental health[2]. For example, researchers at Stanford University in the United States found that the higher the monthly average temperature, the higher the frequency of using depressive words on social networking sites[5]. In addition, extreme high temperatures may also affect social behavior, such as increasing interpersonal conflicts and aggressive behavior[6].

Source: Xinhua News Agency

Exposure to extreme temperatures can also increase the incidence of psychological disorders. And high temperatures are not kind to patients who already suffer from mental illness. Dr. Shah, a professor in the Menninger Department of Psychiatry and Behavioral Sciences at Baylor University, said: "All mental illnesses increase with high temperatures because high temperatures can cause more fatigue, irritability and anxiety, and can exacerbate depressive episodes."

Previous studies of emergency department visits have examined hospital visits related to heat and mental health, with one study reporting an 8% increase in emergency department visits due to the effects of heat on mental health.[7]

02 High temperatures can affect mental health in these ways →

Heat triggers physiological responses in the body, such as increased heart rate and sweating, to help dissipate heat. These responses are essential for maintaining body temperature balance, but they can also have an impact on mental health.

(1) Long-term exposure to high temperatures may cause heat stress, which causes the cardiovascular system to work harder and may lead to a drop in blood pressure and impaired blood circulation.

This physical discomfort can lead to increased psychological stress, as heat stress triggers the release of stress hormones such as adrenaline and cortisol. As levels of these hormones increase, they can cause emotional reactions, leading to irritability, restlessness, and heightened emotional sensitivity.

(2) Rising temperatures can also disrupt sleep patterns and affect mental health

Poor sleep quality caused by heat can lead to irritability, difficulty falling asleep and frequent awakenings during the night. Disrupted sleep can exacerbate existing mental health conditions and lead to feelings of irritability and fatigue. High temperatures can also lead to decreased cognitive function, such as impaired memory, concentration and decision-making, affecting the completion of daily tasks and increasing psychological stress.

Source: Xinhuanet

(3) High temperatures also reduce an individual’s ability to cope with stress

Prolonged exposure to high temperatures can reduce patience and tolerance, and the discomfort and stress associated with heat stress can lower the threshold for stimulation, leading to reduced patience and increased emotional sensitivity in interpersonal interactions. The physiological stress caused by heat stress can weaken psychological resilience.

Resilience refers to people's ability to handle crises and stress and to recover from crises when they are mentally or emotionally troubled. Heat makes it more difficult for us to effectively manage daily stress and challenges. This can lead to increased feelings of stress and decreased emotional control, which can easily lead to "road rage" situations.

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(4) High temperatures can also reduce motivation to participate in activities

The physiological stress of heat can drain energy and dampen enthusiasm, potentially leading to reduced participation in social, work, and leisure activities.

In summary, high temperatures can affect hormones, sleep, cognition, patience, and more, and individuals may find themselves more prone to frustration, impatience, and interpersonal conflict in hot environments, highlighting the complex connection between physical and emotional health.

03 How to reduce the impact of high temperature on mental health?

(1) First, we need to prepare for the basic physical aspects to reduce the impact of high temperatures on us

If dehydration occurs, it will lead to increased discomfort, fatigue, and psychological distress. Therefore, it is recommended to replenish water in time when going out, and if you sweat too much, it is best to replenish electrolyte water. In terms of diet, pay attention to consuming enough fruits and vegetables, which provide important vitamins and minerals to promote the maintenance of optimal body temperature and overall function. In addition, pay attention to avoid overeating. Overeating will lead to increased metabolic heat, which will subsequently cause the body to heat up.

(2) Appropriate clothing selection is also important

Studies have suggested that wearing light, light-colored, loose-fitting clothing can enhance effective cooling of the body, especially clothing made of breathable materials such as cotton or linen [8]. Hats and sunglasses are recommended as additional outdoor protection. Try not to stay outdoors for too long and go indoors to avoid the heat.

(3) Improve the sleeping environment

Create a cool sleeping environment by using fans, air conditioners or taking a cool shower before bed to improve sleep quality. It is worth noting that taking a rest during the hottest hours of the day can help reduce physical and mental fatigue caused by high temperatures, so a lunch break is also a good choice.

(4) Pay attention to your mental health

You can participate in more activities that help reduce stress and promote relaxation, such as listening to music, watching movies, swimming, or exercising. Summer is especially suitable for water sports such as swimming to avoid heat stroke. You can also use mindfulness meditation and stress management techniques for self-regulation. If negative emotions persist and cannot be managed independently, you should seek professional help, such as psychological counseling and psychotherapy, to prevent the development of psychological disorders.

I hope everyone can cool down mentally during the hot summer, have a good green mood, and have a happy summer!

Author: Yi Yi, Master of Applied Psychology, University of Chinese Academy of Sciences

Reviewer: Tang Yicheng, Secretary General of the Science Popularization Committee of the Chinese Psychological Society

Produced by: Science Popularization China

References

1 Barreca, Alan, Karen Clay, Olivier Deschenes, Michael Greenstone, and Joseph S Shapiro, “Adapting to Climate Change: The Remarkable Decline in the US Temperature Mortality Relationship over the Twentieth Century,” Journal of Political Economy, 2016, 124 (1), 105–159.

2 Noelke, C., McGovern, M., Corsi, DJ, Jimenez, MP, Stern, A., Wing, IS, Berkman, L. (2016). Increasing ambient temperature reduces emotional well-being. Environmental. Research. 151, 124–129. doi: 10.1016/j. envres.2016.06.045

3 Chen, N T., Lin, P H., & Guo, YLL (2019). Long-term exposure to high temperature associated with the incidence of major depressive disorder. Science of the Total Environment, 659, 1016–1020. doi: 10.1016/j.scitotenv.2018.12.434

4 Wahid, SS, Raza, WA, Mahmud, I., Kohrt, BA, 2023. Climate-related shocks and other stressors associated with depression and anxiety in Bangladesh: a nationally representative panel study. The Lancet Planetary Health 7, e137–e146.. https://doi.org/10.1016/s2542-5196(22)00315-1

5 Burke, M., González, F., Baylis, P., Heft-Neal, S., Baysan, C., Basu, S., & Hsiang, S. (2018). Higher temperatures increase suicide rates in the United States and Mexico. Nature Climate Change, 8(8), 723–729. doi: 10.1038/s41558- 018-0222-x

6Yu Guoliang, Chen Tingting, Zhao Fengqing. (2020). The impact of temperature and temperature change on mental health. Advances in Psychological Science, 28(8), 1282–12921

7 Nori-Sarma A, Sun S, Sun Y, et al. Association Between Ambient Heat and Risk of Emergency Department Visits for Mental Health Among US Adults, 2010 to 2019. JAMA Psychiatry. 2022;79(4):341–349. doi:10.1001/jamapsychiatry.2021.4369

8 Khosla R, Jani A, Perera R. Health risks of extreme heat. BMJ. 2021;375:n2438. 10.1136/bmj.n2438