Climate breakdown depriving us of sleep, study finds

Rising temperatures could see people lose an average of 58 hours of sleep each year by 2099, Andy Gregory reports

Sleep is ‘an essential restorative process integral for human health and productivity’, researchers say (PA Archive)

Global heating is negatively impacting people’s sleeping patterns around the world, with those in poorer countries worse-affected, a new study suggests.

Providing what they say is the “first planetary-scale evidence” that above-average temperatures “erode human sleep”, scientists have calculated that, by 2099, rising temperatures could see people lose between 50 to 58 hours of sleep each year.

According to the study, published on Friday in the journal One Earth, this deterioration in sleeping patterns could even be among the reasons why – according to a growing body of evidence – climate breakdown is impacting upon individuals’ mental health and cognitive capabilities.

While recent self-reported data from the United States has already suggested that sleep quality decreases during bouts of hot weather, it had previously remained unclear how fluctuations in temperature impact people living across the world in a variety of climates, the researchers said.

In their study, the scientists analysed weather records and anonymised data collected from sleep-tracking wristbands belonging to more than 47,000 adults across 68 countries on every continent except Antarctica.

They found that on nights warmer than 30C, people lost an average of more than 14 minutes of sleep – with the likelihood of getting fewer than seven hours of sleep increasing as temperatures rise.

“Across seasons, demographics, and different climate contexts, warmer outside temperatures consistently erode sleep, with the amount of sleep loss progressively increasing as temperatures become hotter,” said the study’s first author Kelton Minor, of the University of Copenhagen.

Combining their findings with 21 different models of potential climate scenarios, they concluded that, under an intermediate scenario posed by the IPCC in 2014 – which scientists said at the time would likely see global temperatures rise at least 1.5C by 2100 – people will lose an average of 50 hours of sleep each year.

But under the worst-case scenario advanced by the IPCC, people could lose an average of 58 hours of sleep each year.

Furthermore, the study warns that, the elderly, residents of lower-income countries, women, and those already living in hotter climates are disproportionately impacted.

The researchers concluded that, under the worst-case climate scenario, residents in the hottest parts of the world could experience a further 23 hours of temperature-driven sleep loss each year by 2099.

However, they also noted that increased access to air-conditioning could be a reason why those living in wealthier countries see their sleep less impacted by high temperatures, positing that increased access to such technology in poorer nations could potentially help to reduce this disparity.

The study also suggested that impaired sleep could be one of the reasons why rising temperatures have been associated with deteriorations in individuals’ mental and physical health.

For instance, by increasing the likelihood of someone getting less sleep, higher temperatures could “predispose susceptible segments of society to ... anger and aggression, hypertension and adverse cardiovascular outcomes, diminished cognitive performance, elevated risk of accidents and injuries, and compromised immune system functioning”, the study said.

Mr Minor said: “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.”