A recent report from The Lancet highlights the growing impact of climate change on global sleep patterns, revealing a significant increase in sleep loss linked to rising nighttime temperatures. The eighth annual Lancet Countdown on health and climate change report, compiled by 122 global experts, found that high nighttime temperatures have led to a 5% increase in hours of sleep lost worldwide over the past five years compared to the period from 1986 to 2005. Notably, sleep loss peaked in 2023, which is recorded as the hottest year, showing a 6% rise.
This study marks the first time the prestigious medical journal has investigated the correlation between climate change and sleep disruption. According to the report, excessive heat, drought, and heavy rainfall are adversely affecting human health. In 2023 alone, high temperatures resulted in an astounding 512 billion potential hours of labor lost globally. Additionally, heat-related deaths among individuals over the age of 65 reached an alarming high, increasing by 167% compared to the 1990s.
“This isn’t just about extreme weather events,” remarked Jeremy Farrar, chief scientist at the World Health Organization. “This is about every week, every month of the year, and the impact on all of our health.”
The report highlights a concerning trend: nighttime temperatures are rising faster than daytime temperatures in many regions. This not only disrupts sleep but also hampers the body’s ability to cool down, exacerbating heat-related fatalities, particularly among those with pre-existing health conditions such as heart and respiratory issues. Using historic sleep-tracking and temperature data, researchers assessed the effects of high nighttime temperatures on sleep across various years, identifying the Middle East and sub-Saharan Africa as the regions most affected.
In addition, even in more temperate climates, inadequate building design can worsen nighttime overheating, with indoor temperatures often remaining higher than outdoor levels. Experts suggest that enhancing building ventilation and shading could mitigate heat retention, while projections indicate that the demand for air conditioning is set to triple by 2050.
Sleep deprivation poses significant risks, including diminished attention span and overall quality of life, which can exacerbate existing health issues. Kevin Lomas, a professor of building simulation at Loughborough University, noted that in the UK, bedroom temperatures above approximately 27°C (80.6°F) hinder the body’s cooling ability. “Once you start tinkering with how much sleep people get, then the consequences aren’t just relatively trivial things,” Lomas explained. “They can be long term.”
As climate change continues to impact health and well-being, experts emphasize the urgent need for strategies to address these challenges, particularly concerning sleep and temperature regulation.