Rising temperatures due to climate change are negatively impacting our sleep, a study carried out by a team at the University of Copenhagen and published in the online journal One Earth has found.
The findings suggest that by the year 2099 higher temperatures will lead to us losing 50 to 58 hours of sleep per year – roughly one hour per week.
To make the discovery, the team used data collected from accelerometer-based sleep-tracking wristbands that had previously been shown to match up with self-reported measures of wakefulness and sleep.
The dataset included 7 million individual records taken from more than 47,000 adults from 68 countries across all continents except for Antarctica.
The team found that on nights when the ambient temperature exceeded 30˚C sleep declined by an average of 14 minutes. The likelihood of getting less than the recommended seven hours of sleep also increased as temperatures rose.
“In this study, we provide the first planetary-scale evidence that warmer-than-average temperatures erode human sleep. We show that this erosion occurs primarily by delaying when people fall asleep and by advancing when they wake up during hot weather,” said first author Kelton Minor of the University of Copenhagen.
They also found that the effect is even more pronounced for residents from lower-income countries as well as in older adults and females.
Every night, when we go to sleep, our bodies shed heat into the surrounding environment by dilating our blood vessels and increasing blood flow to our hands and feet.
In order for this process to occur efficiently, the surrounding environment needs to be cooler than our bodies, otherwise our sleep becomes interrupted.
The team now hope to expand the study to take in data from an even larger number of participants, especially more vulnerable populations such as those who live in the in the world's hottest and poorest regions.
“In order to make informed climate policy decisions moving forward, we need to better account for the full spectrum of plausible future climate impacts extending from today's societal greenhouse gas emissions choices," said Minor.
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