New research, as presented at the 2017 American Thoracic Society International Conference, found that exposure to increased levels of air pollution over an extended period may be making it difficult to get a good night’s sleep.
Lead author of the study, Martha E. Billings, MD, notes that studies in the past have shown a correlation between air pollution and increased heart disease, as well as decreased lung function and breathing problems; however, unfortunately, very little is known about pollution’s effects on sleep. Dr. Billings is the assistant professor of medicine at the University of Washington, where the research was conducted. She notes that she and her team theorized that since air pollution does cause irritation in the upper airway, congestion, and swelling, it may also be responsible for disruptions in the central nervous system and areas of the brain responsible for controlling our breathing while asleep.
Scientists performed a data analysis of 1863 people in the Multi-Ethnic Study of Atherosclerosis (MESA), who were also part their Sleep and Air Pollution studies. The two most common air pollutants examined were PM2.5 (fine-particles) and NO2 (traffic-related/gas). Data on measurements came from hundreds of Environmental Protection Agency and MESA Air monitoring sites located throughout the United States. Additionally, information was gathered from local environment features and tools. With this data, scientists determined an estimated air pollution level in or around each person’s home at two time points in the study: once at the end of the first year and again at five years.
Participants were asked to wear wrist actigraphy, which monitored and measured all movements, even small ones, during sleep. This information helped researchers determine estimates of sleep and wake patterns over the course of one full week. The data calculates sleep efficiency, which is a measurement tool that determines the amount of time a person spends in bed awake and asleep. Analysis of this information led researchers to determine that sleep efficiency in 25% of the participants was less than 88%. In addition, scientists studied pollution exposures to see if there was an association in those with low sleep efficiency.
Participants were split into fourths, which were determined according to the level of pollution. The 25% of people with the most air pollution were then compared to the 25% of people who had the lowest pollution levels.
The analytical study found that those who had the highest exposure to NO2 over a period of five years were more likely (60%) to have low sleep efficiency when compared to people who had the lowest exposure to NO2. Those who were exposed to higher levels of fine-particle pollution were almost 50% more likely to have decreased sleep efficiency.
Data was adjusted for several factors including body mass, obstructive sleep apnea, race/ethnicity, smoking status, income, age, and socioeconomic status.
Of interest in this research was how long-term exposure to air pollution affected sleep health. Dr. Billings noted that there is likely an acute reaction to short-term exposure to increased air pollution, but the data was insufficient to support this theory. The parent MESA study is currently reviewing the chronic side effects of elevated levels of pollution with regards to heart health.
Findings suggest that there may be a correlation between increased air pollution and poor sleep quality, just as high air pollution levels affect lung and heart health. Improving the quality of the air, even if just within the home, could be a way for people to improve their sleep health and reduce health risks.
As expected, additional research is necessary to explore and discover any links between sleep and pollutants, especially with regards to the mechanisms that may be responsible for disrupting sleep patterns, such as traffic noise leading to poor sleep.
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