Heat and Air Pollution Fueling a Looming Sleep Apnea Crisis
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Rising temperatures and worsening air quality are creating a dangerous confluence, poised to considerably increase the prevalence of sleep apnea, a possibly life-threatening sleep disorder. New research highlights how both heat and pollutants destabilize breathing, worsen existing conditions, and put millions more at risk.
A growing body of evidence suggests a direct link between environmental factors and the severity of obstructive sleep apnea, a condition where the upper airway repeatedly collapses during sleep. “Heat may also destabilize breathing control, increase fluid retention, and promote dehydration, all of which can make the upper airway more collapsible and increase the likelihood of sleep apnea,” explains a researcher at Flinders university.
The Urban Impact: Air Pollution and Breathing
The threat is notably acute in urban environments. Sleep apnea is already projected to become a more widespread problem in cities due to the chronic impact of air pollution on nighttime breathing, a trend expected to accelerate. Last year, a study lead by researchers in Hong Kong revealed that exposure to PM2.5 particles – microscopic airborne pollutants from vehicle exhaust, factory emissions, and wildfires – increases the likelihood of developing sleep apnea, regardless of exposure duration.
These particles, less than 2.5 micrometers in width, can penetrate deep into the lungs and bloodstream, triggering inflammation and airway irritation. Similarly, exposure to nitrogen dioxide, a reddish-brown gas released from exhausts and industrial facilities, has also been shown to exacerbate sleep apnea symptoms. “Air pollutants can increase this instability by irritating the tissues of the throat, making the airway narrower and more prone to collapse when muscle tone naturally falls at night,” says Martino Pengo, an associate professor at the University of Milano-Bicocca.”Nitrogen dioxide is a strong airway irritant and may promote local inflammation that can fragment sleep and destabilize breathing.”
Physiological Effects and Vulnerable Populations
Obstructive sleep apnea occurs when the upper airway becomes unstable and collapses during sleep. Beyond pollution, rising temperatures contribute to the problem. Individuals who are overweight or obese are particularly vulnerable, experiencing more severe episodes of sleep apnea in hot weather as their breathing stops and starts more frequently. This is linked to how excess body fat impacts the body’s ability to regulate internal temperature. “People with higher fat mass tend to retain more heat, and dissipate it less efficiently making it harder to maintain a comfortable core temperature at night,” a researcher notes. “On hot nights, this can lead to lighter and more fragmented sleep.”
Certain demographics face heightened risk. Men, who are more prone to accumulating fat in the neck and possess a naturally more collapsible upper airway, are particularly susceptible. Those with pre-existing mental health or sleep disorders are also at increased risk.
Mitigation Strategies and Future Research
While the findings are concerning, experts are identifying potential mitigation strategies. Martha billings, a professor of medicine at the University of Washington, recommends using indoor air filtering devices when air quality is poor. “I would recommend it especially if the air quality index is greater than 200 as can happen with forest fires or other stagnant air,” she advises.
Losing weight can also help mitigate risk, particularly as temperatures rise. Researchers at Flinders University are working to develop personalized advice and heat-warning systems for those most vulnerable to sleep apnea during heatwaves. They are seeking funding to conduct experiments testing the effectiveness of cooling mattress toppers and behavioral interventions, such as ensuring adequate hydration before bed, in preventing apnea events.
“Ultimately, our goal is to develop practical, evidence-based recommendations that can be applied during heatwaves, particularly for vulnerable groups and people at higher risk,” says a researcher at Flinders University.
