COPENHAGEN, Denmark — Rising temperatures due to climate change will likely mean people are going to get less sleep in the years to come, a new study warns. Researchers from the University of Copenhagen suggest that people will lose up to 10 minutes of sleep at night as a result of global warming by the end of the century.
They found that increasing ambient temperatures negatively impacts human sleep patterns — making people go to bed later and wake up earlier. The team adds their findings suggest that by the year 2099, suboptimal temperatures may erode 50 to 58 hours of sleep per person per year.
They also found that the temperature effect on sleep loss is “substantially larger” for residents in lower income countries as well as in older adults and females.
“Our results indicate that sleep—an essential restorative process integral for human health and productivity—may be degraded by warmer temperatures,” says study first author Kelton Minor in a media release.
“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.”
Heat can have a harmful effect on the body
Researchers note that it’s long been known that hot days increase deaths and hospitalizations and worsen human performance. However, the biological and behavioral mechanisms underlying these impacts have been unclear.
“In this study, we provide the first planetary-scale evidence that warmer-than-average temperatures erode human sleep,” Minor says. “We show that this erosion occurs primarily by delaying when people fall asleep and by advancing when they wake up during hot weather.”
The research team used anonymized global sleep data collected from accelerometer-based sleep-tracking wristbands. The figures included seven million nightly sleep records from more than 47,000 adults in 68 countries spanning all continents except for Antarctica.
Measures from the type of wristbands used in the study had previously been shown to align with independent measures of wakefulness and sleep.
The study, published in the journal One Earth, suggests that on very warm nights – greater than 86 degrees Fahrenheit – sleep declines by an average of just over 14 minutes. The likelihood of getting less than seven hours of sleep also increases as temperatures rise.
“Our bodies are highly adapted to maintain a stable core body temperature, something that our lives depend on,” Minor continues. “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.”
People adapt much better to the cold
In order for our bodies to transfer heat, the surrounding environment needs to be cooler than we are, the study authors say.
Previous lab studies found that both humans and animals don’t sleep as well when the room temperature is too hot or too cold. However, that research was limited by how people act in the real world: they modify the temperature of their sleeping environment to be more comfortable.
In the current research, 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,” Minor concludes.
Minor says that one important observation was that people in developing countries seem to be more affected by the changes, which may result from a lack of air conditioning in those nations.
South West News Service writer Stephen Beech contributed to this report.