New Delhi: Rising night-time temperatures are doing more than making summers uncomfortable. They are also affecting how long people sleep, with India emerging
as one of the global hotspots for climate-related sleep loss, according to a new Climate Central report. Based on an analysis of 107 Indian cities, the study found that people in parts of South India lose between 78 and 91 hours of sleep every year because of heat, with Tamil Nadu reporting the highest climate change-linked sleep loss. The findings, reported by PTI, highlight growing concerns about the impact of warming nights on public health, productivity and overall well-being.
Climate change and sleep loss
The report found that Tamil Nadu recorded the highest climate change-driven sleep loss in the country, with an additional 7.9 hours per person each year linked directly to climate change.
Among major metropolitan cities, Chennai recorded the highest overall annual sleep loss at 93 hours, followed by Mumbai with 84 hours and Kolkata with 80 hours. Bengaluru, meanwhile, registered the strongest climate change signal, with eight hours of sleep loss annually attributed to climate change.
In Maharashtra, people lost an average of 76.3 hours of sleep every year, including 5.8 hours linked to climate change. Residents of Uttar Pradesh lost around 69 hours annually, with 4.9 hours attributed to climate change.
Global trend points to worsening sleep disruption
According to the report, people worldwide lost an average of 56 hours of sleep each year between 2020 and 2025 because of higher night-time temperatures. Of this, around six hours, more than 10 per cent, was directly linked to human-driven climate change.
The analysis covered 1,338 cities globally and found that climate change-related temperature impacts on sleep have at least doubled since the early 1970s, particularly in regions that already experience extremely warm nights.
Experts explain why findings matter
Explaining the significance of the findings, Kristina Dahl, Vice-President for Science at Climate Central, told PTI, “The analysis reveals how climate change is translating into measurable hours of lost sleep for people around the world. By combining the latest climate attribution science with research on how heat affects sleep, we can now quantify a hidden but growing consequence of rising temperatures.”
She added, “Across more than 1,300 cities, climate change has at least doubled temperature-related sleep loss since the early 1970s, showing that the impacts of fossil fuel-driven warming extend beyond extreme weather to undermine one of the most fundamental requirements for human health.”
Health risks linked to poor sleep
Courtney Howard, emergency physician, Chair of the Global Climate and Health Alliance and President-elect of the Canadian Medical Association, told PTI, “Adults need seven to nine hours of sleep per night for optimal health. Increases in night-time temperatures harm human sleep, with a larger effect seen in residents from lower-income countries, older adults and women.”
The report noted that persistent sleep disruption could become a growing public health concern if night-time temperatures continue to rise. Regularly sleeping for less than seven hours has been linked to impaired immunity, reduced productivity, poorer mental health, increased risk of accidents, weight gain, diabetes, hypertension, cardiovascular disease and a higher risk of premature death.
The findings suggest that climate change is affecting health in ways that extend beyond heatwaves and extreme weather events. As nights become warmer, protecting healthy sleep may become an increasingly important part of adapting to a changing climate.
