Climate change has caused around 2.4 billion people to experience at least two more weeks of hot nights each year, with temperatures above 25 degrees Celsius, contributing to sleeplessness and health problems. A new analysis by the non-profit Climate Central has revealed that there is a risk of “an epidemic of sleeplessness, mental health problems, and acute and chronic illnesses caused by climate change. Evidence suggests that nighttime temperatures above 25°C and 20°C, or even 18°C, can negatively impact sleep and health.” Climate Central looked at how anthropogenic climate change has caused nighttime temperatures to rise and how many people have been affected each year between 2014 and 2023.
Italy among the most affected countries
Italy “is in the top 3 of the most affected European countries with two additional weeks of nights above 18°C, two additional weeks above 20°C, and 3 additional nights above 25°C,” reports the study, which also analyzed some large cities: “Naples saw 6 additional nights above 18°C, 20 additional nights above 20°C, and 23 additional nights above 25°C due to climate change; Milan had 61 additional nights above 18°C, 47 above 20°C, and 4 additional nights above 25°C due to climate change; Turin recorded 57 additional nights above 18°C due to climate change; Rome had 24 additional nights above 18°C and 30 additional nights above 20°C due to climate change.”
The risks
“High nighttime temperatures are particularly dangerous because they prevent our body temperature from decreasing and allowing us to regain strength lost during the day,” the research notes. “They therefore increase the risk of stroke, other cardiovascular conditions and mortality. Hot nights significantly reduce the quality and duration of sleep worldwide, resulting in a wide range of negative effects on physical and mental health, cognitive function, learning ability and brain development in children. Short and poor-quality sleep can also shorten life expectancy and increase the risk of accidents and injuries.”
“Nighttime heat – continues the analysis by Climate Central – has a disproportionate impact on the most vulnerable groups: infants, the elderly and pregnant women. The effects of high nighttime temperatures also vary across the world and within each country, lower-income populations are disproportionately affected, partly due to differences in housing quality and the availability of air conditioning. The effects of nighttime heat can be further exacerbated in cities due to the heat island phenomenon, which can result in temperatures in urban areas being significantly higher than in surrounding peripheral and rural areas”.
This analysis uses temperatures measured outside buildings rather than inside them. “An outside temperature of 20 or 25°C can feel higher inside homes due to a variety of factors – building types that are more prone to overheating, lack of ventilation and trapped heat. For the homeless, displaced, in refugee camps or in conflict zones, the scorching heat caused by climate change at night further exacerbates already precarious and dangerous living conditions, with many forced to sleep in makeshift structures or tents that trap heat,” the analysis continues.
Heat waves
“These findings – the research concludes – come against the backdrop of continuing heatwaves around the world that are breaking records and becoming more intense and more likely due to climate change, mainly resulting from the burning of fossil fuels. June 2024 was the thirteenth consecutive month with the highest temperatures on record – an increase of 1.6°C above pre-industrial levels – after eleven consecutive months in which global temperatures were 1.5°C higher than in 1850”.
Michelle Young, Climate Impacts Research Associate at Climate Central, said: “From Indonesia to Iraq to Italy, our analysis shows that climate change is driving higher nighttime temperatures. Each year, around 2.4 billion people are suffering at least two weeks of extra nights above 25°C due to climate change over the past decade. These findings are another stark reminder of the human-induced impact of a warming world, which is disrupting so many lives with hot nights, sleep deprivation and the resulting physical and mental health impacts.”
“With 2024 likely to be the hottest year on record, it has never been more crucial to stop burning fossil fuels like oil, coal and gas and protect forests to prevent further increases in global temperatures,” Young concludes.
