Another consequence of climate change: A good night's sleep
It’s no surprise that a change in our planet’s climate would affect our coastlines, our weather patterns and our food supply. But here’s something you may not have considered before: Global warming might also affect how well we sleep at night.
In a paper published Friday in Science Advances, researchers show that when local temperatures get unusually high people don’t sleep as well as they usually do. And if climate trends continue, we can expect to have more frequent heat waves that also last longer.
“There are going to be lots of impacts of climate change and this is just another factor in a mosaic of negative factors,” said Nick Obradovich, postdoctoral fellow at the Harvard Kennedy School and research scientist at the MIT media lab, who led the work.
It turns out that we actually need to cool down a bit before we go to sleep. Previous research has shown that just before bedtime our core temperature dips, signaling that it’s time for some shut-eye. Our bodies have a few mechanisms for shedding excess heat; the blood vessels in our skin dilate, which helps heat escape through the skin, and our hands and feet get warmer, which helps move heat away from the core. However, lab studies show that the body has trouble shedding its core heat when the room temperature is warm. These studies have also found that elevated core temperature is associated with trouble falling and staying asleep.
Obradovich, who studies the social impact of climate change, was curious if he could find evidence that heat waves and other temperature anomalies had any effect on people in the real world. Obradovich wondered if he could get more quantitative evidence that would show that people don’t sleep as well when the temperature starts to climb. To find out, he turned to a survey of 765,000 US residents that asked respondents to say how many of the past 30 days they felt they did not get enough rest or sleep and compared their answers with weather data at the city level. The results were telling: the higher the temperature was compared to average, the greater the number of nights that people report not being able to sleep well.
Further analysis revealed that hot nights don’t affect all of us the same way. People over 65 are twice as likely to have trouble sleeping on a hot night than their younger neighbours. This might be due to a previously reported result that older people have more difficulty regulating their body temperature than younger folks.
Finally, Obradovich looked at the predicted effects of climate change on temperature in the future and found that, on average, by 2050 rising temperatures will cause six additional night of insufficient sleep per 100 individuals, and by 2099 it will cause an excess of approximately 14 nights of tossing and turning per 100 individuals.
Maybe you don’t think that’s such a big deal. So a bunch of people won’t be able to sleep so well in the future - who cares? Well, keep in mind that insufficient sleep is associated with a whole host of issues including raising the risk of heart disease, diabetes and obesity, as well as a reduction in memory, attention and processing abilities. It also puts people in bad moods and has been linked with the onset of depression. And if all that isn’t bad enough, Obradovich warns that the effects of climate change on sleep might easily be worse in parts of the planet where most people can’t afford to take measures to keep themselves cool.