Sleep Disorders

24 May 2017

Can dirty air keep you awake?

Researchers say that air pollution causes upper airway irritation, swelling and congestion, which may affect breathing patterns and sleep.


Air pollution is a worldwide phenomenon, and according to new research from the World Bank, it kills 20 000 people in South Africa every year, costing the economy nearly R300-million. Not surprisingly, the most polluted part of South Africa is the Johannesburg area. 

Effect on sleep efficiency

According to the latest research air pollution may harm your sleep.

"Prior studies have shown that air pollution impacts heart health and affects breathing and lung function, but less is known about whether air pollution affects sleep," said lead author Dr Martha Billings.

"We thought an effect was likely, given that air pollution causes upper airway irritation, swelling and congestion, and may also affect the central nervous system and brain areas that control breathing patterns and sleep," added Billings, an assistant professor of medicine at the University of Washington.

She and her colleagues looked at more than 1 800 people, average age 68, in six US cities. They wanted to see if the two most common air pollutants – traffic-related pollutant gas (NO2) and fine-particle pollution – affected sleep efficiency. Sleep efficiency is a measure of the percentage of time in bed spent asleep versus awake.

Fine particle pollution

People exposed to the highest levels of NO2 over five years were nearly 60% more likely to have low sleep efficiency than those with the lowest NO2 exposure, the study found.

Those with the highest exposure to fine particle pollution had a nearly 50% increased likelihood of having low sleep efficiency.

The study was presented at an American Thoracic Society meeting in Washington, D.C.

The research can't prove a direct cause-and effect relationship. Still, "these new findings indicate the possibility that commonly experienced levels of air pollution not only affect heart and lung disease, but also sleep quality," Billings said in a society news release.

Read more:

Plants clean air pollution

Air pollution may lower IQ

Air pollution linked to cognitive decline in seniors


Ask the Expert

Sleep disorders expert

Dr Alison Bentley is a general practitioner who has consulted in sleep medicine and sleep disorders, in both adults and children of all ages, for almost 30 years. She also researches and publishes on a number of sleep-related topics both in formal research journals and lay publications including as editor of Sleep Matters, an educational newsletter on sleep disorders for doctors.

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