The world is getting hotter, and not just during the day. Nighttime temperatures are on the rise as well, and this is having an impact on the sleep patterns of people around the globe.
When it comes to a good night’s sleep, temperature matters. That’s the key finding of new research that analyzed data from sleep-tracking wristbands worn by people all over the world.
A new study has found that increased ambient temperatures are leading to shorter sleep duration, particularly through delayed onset of sleep. This is resulting in more cases of insufficient sleep, which can have a range of negative health effects.
The study linked data from sleep-tracking wristbands worn by over 7 million people in 68 countries to local daily meteorological data. After controlling for individual, seasonal, and time-varying confounds, they found that increased temperature was associated with shorter sleep.
The study found that warmer nighttime temperatures are linked with reduced sleep, and the impact is greatest on the elderly, residents of lower-income countries, females, and those already living in hotter climates.
Those in hotter regions were found to experience more sleep loss per degree of warming, suggesting that there is limited adaptation to rising temperatures.
By 2099, it is estimated that suboptimal temperatures will erode 50-58 hours of sleep per person in a year. This will result in geographic inequalities that scale with future emissions.
It is clear that rising temperatures are having a serious impact on our sleep. This is yet another example of how climate change is affecting our lives in a negative way.
The findings have important implications for public health, particularly as the world continues to warm due to climate change.
Sleep is critical for physical and mental health, and a lack of sleep has been linked with reduced cognitive performance, diminished productivity, compromised immune function, adverse cardiovascular outcomes, depression, anger, and suicidal behavior.
Previous research has shown that high ambient temperatures can reduce subjective sleep quality. To fill this knowledge gap, the authors of the new study used data from more than 700,000 people who wore sleep-tracking wristbands for an average of 35 nights. The wristbands, which are worn on the non-dominant hand, measure sleep duration and quality. The data was then linked with global weather and climate measurements, including outdoor temperature, humidity, and barometric pressure. The analysis revealed that warmer nighttime temperatures are indeed linked with reduced sleep, with unequal effects.
Further analysis revealed that elevated ambient temperatures may already be impairing human sleep globally.
“When we looked at the data, we found that there were already signs of sleep being impacted by rising temperatures,” said the study’s author, a data scientist at the Massachusetts Institute of Technology.
“And these effects are only going to become more pronounced in the future as the world continues to warm.”
The findings have important implications for public health, particularly in lower-income countries where residents are more likely to be impacted by rising temperatures.
Without adaptation, the authors estimate that each person could be subjected to an average of 2 weeks of temperature-attributed short sleep each year by the end of the century.
“This is a wake-up call that we need to start adapting to the changing climate.”
“If we don’t, the impacts on human health are going to be very real, and they’re going to be felt most by the people who are least able to adapt.”
So what can we do about it? It’s not a buying a new mattress. The researchers say that one way to combat the effects of rising temperatures on our sleep is to use air conditioning. But they say that air conditioning is not a long-term solution. They say that we need to find ways to reduce the amount of heat-trapping greenhouse gases we're emitting into the atmosphere. Otherwise, we can expect to see more sleepless nights in the future.