Sleepless Nights

Climate change is increasing the frequency of nighttime temperatures exceeding 18°C, 20°C, and 25°C, which impairs human sleep and increases health risks. Between 2018 and 2023, the average person globally experienced 4.8 additional days per year above 20°C and 11.5 additional days above 25°C due to climate change. The report highlights severe impacts in specific regions, such as California in the U.S. and West Bengal and Assam in India, where the number of added hot nights is highest.

• Nighttime temperatures are rising faster than daytime temperatures, leading to a global erosion of sleep quality. This lack of quality sleep is linked to physical and mental health problems, impaired cognitive function, negative effects on children's brain development and school performance, and a higher likelihood of workplace accidents. Additionally, relative mortality risk on days with hot nights can be 50% higher than on non-hot nights.
• On a global average between 2018 and 2023, climate change added 4.8 days per year where minimum nighttime temperatures exceeded 20°C and 11.5 days per year where they exceeded 25°C. Regional impacts vary, with the southwestern US and Brazil seeing increases of 40 days or more above 20°C, while several northern African countries, Saudi Arabia, and southeast Asia saw 40 or more additional days above 25°C.
• In the United States, central and northern California cities—including Merced, Clovis, Fresno, Visalia, Bakersfield, Redding, Chico, Turlock, and Yuba City—experienced the highest increase in nights above 20°C, adding between 45 and 58 days. For the 25°C threshold, the highest increases (40 to 53 days) occurred in Florida, Texas, Louisiana, Nevada, and Arizona, with Port St. Lucie, FL recording 53 additional days.
• In India, climate change has most significantly impacted nighttime temperatures above 25°C, particularly in the states of West Bengal and Assam. Cities such as Jalpaiguri, Guwahatii, Silchar, Dibrugarh, and Siliguri saw between 80 and 86 additional days above this threshold. Mumbai experienced an additional 65 days above 25°C.
• In the United Kingdom, the 18°C threshold is most relevant due to the cooler climate. England experienced the highest increase, with an average of two additional days above 18°C per year. On a city level, Clacton-on-Sea saw the largest increase, with approximately 16 additional days above 18°C and 4 additional days above 20°C per year.

APA

Climate Central (2024). Sleepless Nights. https://assets.ctfassets.net/cxgxgstp8r5d/7qizKUYa5LpVrbRhuRbVjp/08be9c3b6a9842aca434041856df8f4f/Report_-_Sleepless_Nights.pdf

Chicago

Climate Central. Sleepless Nights. 2024. https://assets.ctfassets.net/cxgxgstp8r5d/7qizKUYa5LpVrbRhuRbVjp/08be9c3b6a9842aca434041856df8f4f/Report_-_Sleepless_Nights.pdf.

Wikipedia

{{cite report |author=Climate Central |title=Sleepless Nights |date=20 June 2024 |url=https://assets.ctfassets.net/cxgxgstp8r5d/7qizKUYa5LpVrbRhuRbVjp/08be9c3b6a9842aca434041856df8f4f/Report_-_Sleepless_Nights.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{climatecentral2024sleepless, author = {{Climate Central}}, title = {{Sleepless Nights}}, institution = {Climate Central}, year = {2024}, month = jun, url = {https://assets.ctfassets.net/cxgxgstp8r5d/7qizKUYa5LpVrbRhuRbVjp/08be9c3b6a9842aca434041856df8f4f/Report_-_Sleepless_Nights.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }