How does rising global temperature impact our sleep quality?

Welcome to this edition of?Sleepletter?where we offer you easy-to-read insights from the latest research papers from the field of sleep neurobiology and clinical sleep medicine. We hope you enjoy the content!

The impact of global warming on sleep quality

It’s well known that ambient temperatures around the world are increasing significantly. In fact, the global temperature has increased at an average rate of +0.18°C (+0.32°F) per decade since 1981. Apart from worsening many types of natural disasters and considerably impacting the flora and fauna worldwide, higher temperatures can have a profound effect on human health. Studies have shown that rising temperatures are associated with infectious diseases, as well as worse respiratory, cardiovascular, neurological and mental health outcomes. However, significantly fewer studies evaluated the effects of temperature on one of the main pillars of health - sleep quality.?

Temperature, more specifically core body temperature, plays an integral role in regulating sleep as its reduction precedes sleep onset. Core body temperature remains low throughout the night and rises again shortly before waking up. One can easily see how rising ambient temperatures can disrupt sleep, and thus increase the risk of many severe conditions such as diabetes, high blood pressure and dementia. With the prevalence of sleep disturbances on the rise, could this actually be attributed, at least partly, to rising temperatures??

One of the first large studies to establish a connection between sleep disturbances and ambient temperature published 5 years ago sparked considerable curiosity in this topic. The study evaluated sleep data from more than 750 000 people from 2002 till 2011 and coupled it with nighttime temperature data. This substantial effort led to the conclusion that increases in nighttime temperatures amplify the number of self-reported nights of insufficient sleep, especially among the elderly and those in lower income brackets. The researchers also estimated that a 1°C rise in nighttime temperature produces an increase of approximately 3 nights of insufficient sleep per 100 individuals per month. If we were to look at the effect that 1°C increase would have on the population of the United States, it would produce nearly 9 million additional nights of insufficient sleep per month or approximately 110 million extra nights of insufficient sleep annually. Quite a bit of nights for only 1°C, right??

Since the global temperature rise is not really slowing, what about the impact of future temperatures on our sleep? Well, the study estimated that in the year 2050 there will be around double the number of sleep disturbances associated with ambient temperature rise, and that number will be five times higher in the year 2099 compared to today. Another study also showed that if temperatures keep rising at the current rate, each person could be subjected to an average of 2 weeks of temperature-attributed short sleep each year by the end of the century.

I know, 2099 is a bit far (maybe too far), but the point is that rising temperatures seem to potentiate the already high prevalence of sleep disorders. If sleep disturbances are related to higher temperature, you might ask: why just not turn on the air conditioning during the night? While this is a valid point, some parts of the world do not have regular access to it, and others who do might not like the effect that AC has on?drying out your nose, mouth, throat, and skin. What’s more, keeping the AC on in every household during the nighttime does not really help global warming, does it?

While the impact of global warming on health is not new, the research surrounding its effect on sleep is still novel. The studies we went through show an important correlation between rising temperatures and the prevalence of sleep disturbances, and also point to disturbing futures predictions when it comes to sleep loss. Yet, many questions remain. Will other studies show the same correlation? Possibly. Will people adapt to rising temperatures in the future through certain technological or environmental developments so their sleep is less impacted? Maybe. Will the rate of temperature increases seen in the past decades persist till 2099? We don’t know.?

In spite of these uncertainties, one thing is clear: sleep is an incredibly important part of every person’s life and we should aim to preserve its quality as much as possible not only to feel better the next morning, but also to be healthier people in our later stages of life, and maybe even in 2099.

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About the author

Alen Juginovi??is a medical doctor and postdoctoral researcher in the Department of Neurobiology at Harvard Medical School in Boston, MA, USA studying the effect of poor sleep quality on health. He is also organizing international award-winning projects such as Nobel Laureate conferences, international congresses, concerts and other, as well as participating in many events as a speaker. Feel free to contact him via LinkedIn for any inquiries.