An international evidence review by the Johns Hopkins University School of Nursing showed that air pollution affects how well we sleep, as reported by The Guardian.

Review leader Dr. Junxin Li shared that "the signal was stronger and more widespread than we expected. Across dozens of studies, long-term exposure to outdoor pollutants such as particle pollution, nitrogen dioxide, and even carbon dioxide was linked to shorter or lower-quality sleep."

The evidence review compiled 25 studies from around the globe, with 1.2 million people studied from six countries, including the U.S., focusing on people over 45 years old. Some studies measured sleep with devices on subjects' wrists, and other studies used interviews. Both short-term and long-term exposure and indoor and outdoor pollution were examined.

What's happening?

The study showed that pollution influences the way humans sleep. 

It focused on older adults because older people are more likely to spend more time at home, so the sources of pollution could be more closely monitored.

In studies primarily conducted in China, people who used solid fuel in their homes, such as wood or coal, were compared to people who used clean fuels. Households using solid fuel had poorer sleep quality. Effects included insomnia and short sleep duration. Studies in the UK showed similar results, especially in households that cooked with gas stoves.

One of the studies used in the data pool found that using an extractor to improve air quality or opening a window while cooking reduced the negative impact the interior pollution had on sleep.

Why is the effect of air pollution on sleep important?

Sleep plays a critical role in overall human health. It helps physical performance, improves brain function, and supports our immune systems. Lack of sleep can lead to a range of health issues, including increased stress and a decline in mental health.

The pollution sources in the study were all human-created, meaning we have control over this factor in our environment.

What's being done about air pollution as it relates to sleep?

The results of the compilation of evidence can be used to predict health effects and sleep problems that may potentially occur due to pollution, and give scientists the opportunity to champion clean air policies and other methods to cut pollution.

Do you worry about the quality of the air inside your home? Yes — often 😬 Yes — but only sometimes 😕 Only when it's bad outside 😮‍💨 No — I never do 😌 Click your choice to see results and speak your mind.

One of the conclusions Li drew was that findings indicated that clean-air policies — focused primarily on outdoor sources — need to expand to include indoor sources.

According to The Guardian, Li said, "Air quality — both outdoors and inside the home — is an underrecognised contributor to sleep problems in middle and later life. Sleep itself should be treated as a core health indicator when environmental regulations are evaluated, because cleaner air not only safeguards lungs and hearts, it also helps people sleep, supporting cognition, mood and overall resilience later in life." 

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