Populations in southern India are among those most affected by sleep loss due to climate change, study says

Rising temperatures are leading to an increase in sleep loss among the population in Tamil Nadu and India, a recent study by Climate Central, a non-profit organization, has pointed out.

According to their analysis of 11 cities in Tamil Nadu – Chennai, Coimbatore, Erode, Kallakurichi, Madurai, Salem, Theni, Tiruchi, Tirunelveli and Tiruppur, the researchers estimate that sleep loss due to climate change has increased between 4% and 7% in each of the 101 Tamil cities. 2025-2025. In Puducherry, sleep loss increased by three percent during the same comparable periods.

The research studied sleep loss due to climate change in more than 1,338 cities worldwide, including 107 cities in Puducherry, Andhra Pradesh, Kerala, Tamil Nadu, Gujarat, Telangana, Odisha, Chhattisgarh, Maharashtra, West Bengal, Bihar, Karnataka, Assam, Jharkhand, Hary U Rajasthan, Delhi and Madhya Chandigarh is analyzed in India.

Responding to questions from The Hindu, Kristina Dahl, vice president of science at Climate Central, explained the methodology scientists use to estimate the sleep loss of people living around the world. “Minor et al. In their 2022 study on how rising temperatures are eroding human sleep globally, they modeled temperature and sleep using sleep data from a recent period. Our analysis applies a published model to nighttime temperatures from 2020-2025 and 1970-1975 to estimate the expected loss of sleep under these temperature conditions. They compare the effect of nighttime temperature on the same changes in time during the same changes in individuals, while in within the same sleep time model, we apply this published relationship to observed and counterfactual nighttime temperatures.Our analysis does not account for all sleep loss from all causes, and the portion attributable to climate reflects the difference between observed nighttime temperatures and nighttime temperatures in a world without anthropogenic warming.

The researchers note that southern India has emerged as a hotspot for sleep disruption, with Tamil Nadu, Kerala, Andhra Pradesh, Karnataka and Telangana experiencing the highest total sleep loss from all factors, including climate change, with high nighttime temperatures linked to increased risk of stroke, other cardiovascular disease and mortality. “Globally, hot nights also reduce the quality and duration of sleep, which has a wide range of negative effects on physical and mental health, cognitive function and brain development and learning in children. Short and poor-quality sleep can also shorten life expectancy and increase the risk of accidents and injuries,” they note.

Puducherry had the highest observed annual sleep loss per person at 92 hours, followed by Andhra Pradesh at 88.6 hours and Kerala at 88.3 hours. However, Tamil Nadu has emerged as the state with the most population affected by climate change-related sleep loss, with the average person losing around 7.9 additional hours of sleep per year due to climate change, the highest in the country. Meanwhile, in Karnataka, the average person lost around seven hours of sleep every year due to changing weather.

Data from major Indian cities showed that while Chennai had the highest observed sleep loss per person per year in the country with 93 sleep losses, climate change could cause a loss of six percent or five hours of sleep per person. But climate change has caused 8 hours of sleep loss per person in Bengaluru, or 12 percent of the annual figure, the most among major Indian cities.

Dr. Dahl said people in higher-income countries were less affected by the changing climate, suggesting that access to better cooling could help reduce heat-related sleep loss.

“In urban areas, adaptation measures that reduce the urban heat island effect, such as planting trees and painting roofs white, could also help. Such things reduce the amount of heat that gets trapped in the urban environment, which tends to make cities warmer than their surrounding areas. Ultimately, to minimize future heat-related sleep loss, countries around the world will need to reduce heat-trapping emissions faster and more sharply because the more we warm, the more we lose the planet, the more it warms, added.

Published – Jul 17, 2026 0:47 AM IST