Advertisement

Climate change ‘could wreck your sleep’, new study warns

Depressed woman awake in the night, she is touching her forehead and suffering from insomnia
Climate change could cost us all dozens of lost hours of sleep, a new study has suggested. (Getty)

Climate change isn’t just going to make sea levels rise and make summers intolerably hot – it could wreck your sleep, too, a new study has suggested.

In fact, by the end of the century, the average person could lose 50 to 58 hours of sleep per year due to warming temperatures, the University of Copenhagen researchers say.

The researchers say that the change will impact people from lower-income countries the hardest, as well as older people.

Lead author Kelton Minor, of the University of Copenhagen, said: "Our results indicate that sleep – an essential restorative process integral for human health and productivity — may be degraded by warmer temperatures.

"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."

Read more: Melting snow in Himalayas drives growth of green sea slime visible from space

Previous research on the impact of climate change has focused on economic and societal health outcomes on a broad scale.

It's long been known that hot days increase deaths and hospital admissions and worsen human performance, yet the biological and behavioural mechanisms underlying these impacts have not been well understood.

Recent self-reported data from the US has suggested that subjective sleep quality decreases during periods of hot weather, but how temperature fluctuations may impact changes in objective sleep outcomes in people living across a variety of global climates has remained unclear.

Minor said: "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."

Read more: A 1988 warning about climate change was mostly right

The investigators used anonymised global sleep data collected from accelerometer-based sleep-tracking wristbands.

The data included 7 million nightly sleep records from more than 47,000 adults across 68 countries spanning all continents except for Antarctica.

Measures from the type of wristbands used in this study had previously been shown to align with independent measures of wakefulness and sleep.

The study suggested that on very warm nights (greater than 30 degrees Celsius), sleep declines an average of just over 14 minutes. The likelihood of getting less than seven hours of sleep also increases as temperatures rise.

Read more: Why economists worry that reversing climate change is hopeless

"Our bodies are highly adapted to maintain a stable core body temperature, something that our lives depend on," Minor added.

“Yet every night they do something remarkable without most of us consciously knowing — they shed heat from our core into the surrounding environment by dilating our blood vessels and increasing blood flow to our hands and feet."

He added that in order for our bodies to transfer heat, the surrounding environment needs to be cooler than we are.

The investigators found that under normal living routines, people appear far better at adapting to colder outside temperatures than hotter conditions.

"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.”

Watch: Climate change activists protest in Davos