The first systematic review investigating the relationship between climate change and human sleep revealed a consistent link between impaired sleep and rising temperatures and weather events associated with climate change. The review suggests that the most vulnerable people, including the elderly and the impoverished, are most affected.
“Temperatures in the U.S. have increased by 1.3-1.9 °F since 1895, with most of the increase since 1970,” says Melissa Perry, ScD, MHS of the George Washington University Milken Institute School of Public Health (Milken Institute SPH). “Rising temperatures related to climate change cause extreme heat events, which are the leading cause of weather-related deaths in the U.S. Extreme weather events such as hurricanes can also displace vulnerable populations and affect mental health.”
“Scientists know that food and water borne diseases, including salmonella, are prevalent at higher temperatures,” Perry says. “Vector borne illnesses, such as dengue fever and Lyme disease, have been spreading northward as the result of climate change.” However, while many of the health consequences of climate change are well-documented, the effect of climate change on sleep has not been a topic of much investigation among sleep medicine or climate change experts.
Daniel Rifkin, MD, MPH, a sleep medicine expert at the Sleep Medicine Centers of Western New York, first recognized this gap when he took the Milken Institute SPH’s Environmental and Occupational Health in a Sustainable World class a few years ago as an MPH@GW student. “I’ve been interested climate change since I took that course,” he says.
Addressing a research gap
When the time arrived for Rifkin to complete the culminating experience project that both residential and online Milken Institute SPH students complete at the end of their studies, he decided to combine his knowledge of sleep medicine with his newfound interest in climate change. “As I started to peruse the literature, I was amazed at the minimal amount of research out there,” says Rifkin, who is also affiliated with the University at Buffalo’s Jacobs School of Medicine and Biomedical Sciences.
Like many Milken Institute SPH students, he chose to conduct a systematic review for his culminating experience project. Rifkin’s advisor for the project was Michael Long, SD, MPH of the Milken Institute SPH’s Department of Prevention and Community Health. Perry became involved because Rifkin was enrolled in Perry’s online Researching Climate Change and Human Health class when he was working on the project. “She gave me much guidance along the way,” Rifkin says.
Rifkin, Perry and Long uncovered 16 studies which reported a consistent link between temperature and weather events associated with climate change and impaired sleep. Although climate change is known to enhance air pollutants including ozone, which can exacerbate sleep-related breathing disorders, they did not include studies focusing on air pollution due to a recent systematic review on the subject.
“Our review found a consistent link between temperature and weather events associated with climate change and impaired sleep. Total sleep time was diminished due to sleep disruption,” Rifkin says. “However, most of the studies relied on self-reported data, which is a concern because subjective sleep quality often differs from objective measurements.”
Highlighting equity challenges
The review included six studies on the effects of rising temperature on sleep, some of which found that the elderly and lower-income patients were more negatively impacted. “The negative effects of climate change are more severe for vulnerable populations. The disparities in sleep health outcomes highlight yet again the health equity challenges that must be overcome when designing climate change mitigation strategies,” Long says.
“Sleep health should be included as an integral part of any climate resilient system,” Rifkin argues. Because the study found gaps in the literature and to enhance scientists’ understanding of how climate change impacts sleep and to guide future research, he worked with Perry and Long to create a conceptual framework. It highlights the known consequences of climate change as they relate to non-communicable diseases that have links to sleep issues including depression, dementia, Type II diabetes, heart disease and stroke.
“Climate change and sleep: A systematic review of the literature and conceptual framework” is published in Sleep Medicine Reviews.