Global warming leading to sleep loss, greater disparities

According to a recent study, global warming is causing shorter sleep durations around the world, which could increase health risks, especially for the elderly, women and people in low-income countries.

Researchers warn that rising temperatures could lead to growing global disparities in productivity and health if unmitigated climate change continues, according to the global study published in May in the journal One Earth.

Icebergs calved from the Sermeq Kujalleq Glacier (rear) float in the Ilulissat Icefjord on September 5, 2021 in Ilulissat, Greenland. (Getty/Kyodo)

With higher nighttime temperatures, people are already losing 44 hours of sleep per year on average, which is 11 additional nights less than the recommended seven hours of sleep.

Researchers from Danish and German institutions used data collected from 47,628 adults fitted with sleep tracking wristbands in 68 countries and linked it to local weather data recorded from 2015 to 2017.

Rising nighttime temperatures can affect health and behavior by increasing sleep loss, they said.

Sleep deprivation has been associated with “reduced cognitive performance, decreased productivity, compromised immune function, adverse cardiovascular outcomes, depression, anger, and suicidal behavior,” according to the study.

He found that in warmer nighttime temperatures, people fall asleep later and wake up earlier, with sleep loss and the risk of insufficient sleep increasing sharply when nights exceed 10°C.

While rising temperatures affect sleep in general, the elderly, women, people living in low-income countries and those who already live in warmer regions are disproportionately affected, according to the study.

For every degree of temperature increase, people over 65 lost almost twice as much sleep as other age groups, while women slept a quarter less than men.

People in low-income countries were about three times more likely to be sleep deprived than people in high-income countries, and those who already lived in warmer regions lost significantly more sleep.

According to the study, the annual sleep loss could reach around 50 hours per person if greenhouse gas concentrations remain relatively stable and up to 58 hours if they rise sharply.

Nighttime low temperatures above 25°C increase the likelihood of sleeping less than seven hours by 3.5 percentage points compared to temperatures of 5-10°C, while people lose 14 minutes of sleep when nights exceed 30 °C, according to the study.

There was little evidence showing bodies adapt to warmer-than-usual temperatures, making policy and technological interventions that reduce outdoor heat crucial, he said.

Researchers have warned that while cooling technology can promote sleep, it can also increase greenhouse gas emissions and displace ambient heat, without necessarily solving global disparities in sleep.

The study likely underestimated the magnitude of the impact of climate change because the sample was made up of self-selected participants, with more men and people mainly from wealthier countries, he said. note.

Coverage was also sparse for large parts of Africa, Central and South America and the Middle East – regions that already rank among the hottest in the world, he said.

Teresa H. Sadler