Global warming reduces sleep quality, elevates disease risk

According to new research led by the University of California, Los Angeles (UCLA), global warming is reducing sleep quality – a feature that makes it harder for the body to fend off infections or to produce sufficient quantities of antibodies after vaccinations. These findings regarding the deep connection between high temperatures, poor sleep, and reduced immune responses could contribute to our understanding and fight against current health hazards such as Covid-19, the recent monkeypox outbreak, or the resurgence of polio in places such as London or New York.

“No one has previously put together this notion that the ongoing climate crisis is contributing to sleep disturbance and that it’s possibly contributing to the altered risk of infectious disease we’re seeing,” said study author Michael Irwin, a professor of Psychiatry and Behavioral Sciences at UCLA.

According to Professor Irwin, there is a strong correlation between sleep and thermoregulation. Experimental studies have provided evidence that reducing air temperature improve sleep quality by maintaining a normal body temperature without expanding excess energy, while increases in air temperature result in increased wakefulness. 

High-quality sleep helps prepare the body’s responses to possible injuries or infections which may occur the following day, while disrupted sleep contributes to increases in inflammation and dampens the body’s ability to fend off infections. In addition, sleep duration is also strongly associated with infectious disease risks. Longer sleep duration decreases viral or bacterial load, and improves survival rates in a variety of infectious disease models.

Moreover, previous studies have shown that poor sleep could also result in decreased responses to vaccination. For instance, people who had four consecutive nights of low-quality sleep before receiving a trivalent influenza vaccine had a 50 percent reduction in antibody levels. Finally, recent studies on Covid-19 outcomes have found that significant sleep disturbances are associated with an over two-fold increase in the mortality risks for patients infected with SARS-CoV-2. 

Future research is needed to evaluate how altering ambient temperatures affects sleep and, consequently, immune responses. Moreover, studies assessing how rising temperatures may be affecting diverse and disadvantaged communities – such as low-income people without access to air conditioning – should be urgently conducted.

“Just like the pandemic is impacting socioeconomically disadvantaged and ethnic groups disproportionately with more morbid outcomes, it might be that the increases in ambient temperature we’re seeing are further exaggerating those risk profiles,” Professor Irwin concluded. 

The study is published in the journal Temperature.

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By Andrei Ionescu, Earth.com Staff Writer