Dehradun: Climate change is increasingly adding to sleep loss in India, with people in some of the country’s hottest and most humid regions losing up to 90 hours of sleep every year because of high night-time temperatures, according to a new analysis by Climate Central, a global climate research organisation.The report identifies southern India as one of the world’s major hotspots for heat-related sleep loss, with Tamil Nadu, Kerala, Andhra Pradesh, Karnataka and Telangana recording some of the highest levels of disruption. Researchers warned that hotter nights — driven by global warming and the urban heat island effect — are emerging as a growing public health concern, particularly in densely populated Indian cities.The analysis found that residents of Puducherry lose an average of 92 hours of sleep annually because of high night-time temperatures, the highest in the country, followed by Andhra Pradesh at 88.6 hours and Kerala at 88.3 hours. Tamil Nadu recorded the strongest climate change signal, with 7.9 additional hours of sleep loss per person every year directly attributable to climate change, narrowly ahead of Karnataka at 7.8 hours and Rajasthan at 7 hours.Among India’s largest metropolitan cities, Chennai recorded the highest overall sleep loss, with residents losing an average of 93 hours annually, of which five hours were linked directly to climate change. Mumbai, at 84 hours, and Kolkata, at 80 hours, followed, reflecting persistently warm and humid nights.Bengaluru emerged as the city where climate change is having the greatest impact on sleep. Residents here lose an additional eight hours of sleep annually because of climate change — the highest among India’s major metros — with nearly 12% of all temperature-related sleep loss attributed to global warming. Hyderabad recorded seven additional hours of climate-driven sleep loss each year, while Ahmedabad and Pune lost six hours each. Although Delhi recorded the lowest overall sleep loss among the eight metros, at 66 hours annually, the report found that climate change still accounted for an additional five hours of lost sleep every year. “This 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. 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,” said Kristina Dahl, Climate Central’s VP for science.The study said poor sleep is associated with a wide range of health risks, including impaired cognitive performance, poorer mental health, weakened immunity, cardiovascular disease and lower productivity. These impacts are likely to be particularly severe in India, where millions live in densely populated cities that remain warmer after sunset because of the urban heat island effect. Older adults, women, low-income households and people without access to adequate cooling are among the most vulnerable, the study said.The findings are part of Climate Central’s first global analysis to directly estimate how much sleep has been lost because of climate change by combining research on the relationship between temperature and sleep with climate attribution science.Globally, the report found that the average person lost nearly 56 hours of sleep every year during 2020-2025 because of high night-time temperatures, with more than 10% of that loss directly attributable to climate change caused primarily by fossil fuel emissions and deforestation.The study also found that climate-related sleep loss has at least doubled since the early 1970s across all 1,338 major cities analysed worldwide. Cities in the Middle East recorded the highest climate change-attributable sleep loss, with residents in parts of Saudi Arabia, Oman and the United Arab Emirates losing between 12 and 16 hours of sleep annually because of climate change alone.