Southern India faces highest climate-linked sleep loss, new study finds
A recent analysis by the non-profit organization Climate Central has found that rising nighttime temperatures due to climate change are disproportionately affecting sleep in southern India. The study, which examined data from 1,338 cities worldwide, including 107 in India, estimates that sleep loss attributable to climate change has increased by 4 to 7 percent in 11 cities in Tamil Nadu between 1970-1975 and 2020-2025.
The research applies a temperature-sleep model developed in a 2022 study by Minor et al., which used sleep tracking data to quantify how higher nighttime temperatures reduce sleep duration. By comparing observed nighttime temperatures from recent years with counterfactual temperatures in a world without human-caused warming, the researchers isolated the climate change contribution to sleep loss.
Southern states—Tamil Nadu, Kerala, Andhra Pradesh, Karnataka, and Telangana—emerged as hotspots, recording the highest overall sleep loss from all factors, including climate change. The study notes that hot nights are linked to increased risk of stroke, cardiovascular conditions, and mortality, as well as degraded sleep quality with negative impacts on physical and mental health, cognitive functioning, and children's development.
Among Indian states, Tamil Nadu had the highest climate-attributed sleep loss, with the average person losing an additional 7.9 hours of sleep per year due to climate change. Puducherry recorded the highest observed annual sleep loss per person at 92 hours, followed by Andhra Pradesh (88.6 hours) and Kerala (88.3 hours). In major cities, Chennai had the highest observed sleep loss at 93 hours per person annually, but climate change accounted for 5 hours (6 percent) of that. Bengaluru saw the highest climate-attributed share: 8 hours per person, or 12 percent of annual sleep loss.
Kristina Dahl, vice president for science at Climate Central, explained that the analysis estimates only the sleep loss associated with higher nighttime temperatures, not all causes. She noted that people in higher-income countries were less affected, likely due to better access to cooling infrastructure. The findings underscore the uneven impact of climate change on vulnerable populations.
