Heat exposure is linked to increased risks of adverse mental health outcomes in children and young peopleClimate change is increasing the frequency and severity of extreme heat and heatwaves, posing significant risks to public health, particularly among children and young people. Rising temperatures have been associated with adverse mental health outcomes, including increased emergency department visits, anxiety and depression, and suicide attempts. Children and young people may be particularly vulnerable to heat due to their physiological and behavioral susceptibility. Global systematic reviews have reported strong links between heat exposure and adverse mental health outcomes. However, previous reviews have largely focused on the general population or older adults, while evidence among children and young people remains limited and inconclusive. This global systematic review and meta-analysis therefore aimed to examine the mental health impacts of heat exposure in children and young people.
Researchers systematically searched academic databases for epidemiological studies that examined the relationship between ambient temperatures or heatwaves and mental health outcomes in children and young people (age 0–25). Only studies published in English were eligible for inclusion. The search identified 23 studies, published between 2003 and 2024. Nineteen studies examined high temperature exposure and four studies examined heat wave exposure. The included studies reported morbidity-related mental health outcomes, such as emergency-department visits, hospital admissions, outpatient visits, crisis-support calls, and diagnosis-specific outcomes. Together, the studies included roughly 26 million children and young people. Most studies were conducted in the US (10) and China (3). Three studies examined Mediterranean climate zones, four humid subtropical climate zones, and several studies spanned multiple climate zones. No studies were conducted in the Pacific region or Africa. Risk of bias assessments indicated that most high-temperature studies were reliable, but many did not account for other factors that could affect the results, while heatwave studies had more concerns about how participants and exposure were assessed. Separate meta-analyses were conducted for high temperature and heatwave exposures. Analysis also examined differences based on age, climate zone, country income status, and cumulative heat exposure. Five studies were excluded from the meta-analysis due to variation in exposure measures.
Synthesis of 14 high temperature exposure studies found that each 1-degree Celsius increase in temperature was associated with a 0.9% increase in the risk of adverse mental health outcomes in children and young people. Examination by age group did not detect this relationship in the 0–5 age group (2 studies); however, elevated risks were documented in children and young people ages 5–25. Differences were also observed by climate type. The highest risks were found in the hot-summer humid continental and humid subtropical climates. On the other hand, the relationship between higher temperatures and adverse mental health outcomes was not found in the temperate oceanic or monsoon-influenced humid subtropical climates. The relationship was stronger in high-income countries (8 studies), where each 1-degree Celsius increase in temperature was linked to a 1.4% increase in mental health risk. Among middle-income countries (6 studies), no clear relationship was identified. Risk was also higher in countries with greater cumulative heat exposure (11 studies) compared with those with lower overall exposure (3 studies). Studies conducted during warm seasons detected higher risk than year-round studies. The overall synthesis of all four heatwave exposure studies did not detect a relationship with adverse mental health outcomes in children and young people; however, subgroup analysis identified some associations. While no link was found between heatwave exposure and mental health among children ages 0–5, children ages 5–18 showed a 25.3% higher risk of poor mental health outcomes with heatwave exposure. No studies examined heatwave exposure and youth 18 years and older. Heatwave exposure was also linked to adverse mental health outcomes in high-income countries (3 studies). Countries with low cumulative heatwave exposure (2 studies) had a 7.2% increased risk, while countries with high cumulative exposure (2 studies) did not reveal a clear relationship. Findings from the five studies excluded from the meta-analysis were generally consistent with the overall findings of adverse effects of heat exposure on mental health outcomes.
This first systematic review and meta-analysis to synthesize the global evidence on the mental health impacts of heat exposure in children and young people highlights the vulnerability of child and adolescent mental health in the context of a warming climate. The findings provide strong evidence that increases in daily temperature are associated with increased risks of adverse mental health outcomes. These risks were highest among children aged 5–18 years, in high-income countries, in humid subtropical and hot-summer humid continental climates, and in regions with high cumulative exposure to elevated temperatures. Higher risks in high-income countries may be partly due to better healthcare and reporting systems that detect more heat-related mental health cases, while lower risks in middle-income countries may reflect under-reporting and weaker healthcare systems rather than lower actual vulnerability. Although no clear association was identified between heatwaves and adverse mental health outcomes, the limited number of available studies may have contributed to these findings. Further research is therefore needed to clarify the relationship between heatwaves and mental health outcomes in children and young people. Findings also highlight important gaps in the evidence base and priorities for future research, including the need to prioritize low- and middle-income countries and socio-economically disadvantaged populations. Longitudinal studies are also needed to better understand the long-term mental health impacts of sustained heat exposure during childhood.
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