Why Bengaluru faces India's biggest climate sleep challenge despite Chennai topping the sleep loss chart
Hotter nights are quietly becoming one of climate change's most overlooked health impacts, reducing sleep quality and duration across India. New data shows southern states and major metros are bearing the brunt, with some cities losing nearly four days' worth of sleep every year due to rising nighttime temperatures.
- Jul 15, 2026,
- Updated Jul 15, 2026 3:33 PM IST
Climate change is increasingly disrupting not just weather patterns but also people's sleep. A new analysis by Climate Central has identified India as one of the global hotspots for climate-related sleep loss, with hotter nights causing residents in several states to lose dozens of hours of sleep every year. The findings show that while Chennai records the highest overall sleep loss among India's major metros, Bengaluru faces the strongest climate change-driven impact, underscoring how rising nighttime temperatures are becoming a growing public health concern.
The report analysed 1,338 cities globally and found that southern India experiences 78 to 91 hours of annual sleep loss, with 8 to 9 hours directly attributable to climate change. Researchers linked poor sleep caused by hotter nights to impaired cognitive performance, weaker immunity, cardiovascular disease, poorer mental health and reduced productivity.
Sleep loss hotspots
The study found that Puducherry recorded the highest overall sleep loss in India at 92 hours per person annually, followed by Andhra Pradesh (88.6 hours), Kerala (88.3 hours) and Tamil Nadu (84 hours). Gujarat (81.4 hours), Telangana (78.5 hours), Odisha (78 hours) and Chhattisgarh (77 hours) also ranked among the most affected states.
However, when researchers isolated the impact of climate change, Tamil Nadu topped the list, with residents losing an additional 7.9 hours of sleep every year because of global warming. Karnataka followed closely at 7.8 hours, while Rajasthan recorded 7 hours of climate-driven sleep loss. Maharashtra, despite having the largest representation in the study with 22 cities, recorded 76.3 hours of annual sleep loss, including 5.8 hours linked to climate change.
India's sleep map: States with the highest annual sleep loss (2020–2025)
| Rank | State/UT | Annual sleep loss (hours/person) | Sleep loss due to climate change (hours/person) |
| 1 | Puducherry | 92.0 | 5.0 |
| 2 | Andhra Pradesh | 88.6 | 5.8 |
| 3 | Kerala | 88.3 | 6.0 |
| 4 | Tamil Nadu | 84.0 | 7.9 |
| 5 | Gujarat | 81.4 | 5.6 |
| 6 | Telangana | 78.5 | 6.5 |
| 7 | Odisha | 78.0 | 5.3 |
| 8 | Chhattisgarh | 77.0 | 6.0 |
| 9 | Maharashtra | 76.3 | 5.8 |
| 10 | West Bengal | 75.0 | 5.6 |
Chennai and Bengaluru
Among India's eight major metropolitan cities, Chennai recorded the highest overall temperature-related sleep loss at 93 hours annually. Mumbai ranked second with 84 hours, followed by Kolkata at 80 hours.
Yet Bengaluru emerged as the city most affected by climate change. Residents lose an additional 8 hours of sleep each year because of climate change alone, the highest among India's metros. Nearly 12% of Bengaluru's total temperature-related sleep loss is now attributable to climate change.
MUST READ: Why Mumbai becomes a 'bathtub' every monsoon: Key factors behind the flooding
Hyderabad follows with 7 climate-driven hours of sleep loss annually, while Ahmedabad and Pune each record 6 hours. Although Delhi reports the lowest overall sleep loss among the major metros at 66 hours per year, climate change still accounts for 5 additional hours of lost sleep annually.
India's metro cities: Overall sleep loss vs climate change impact (2020–2025)
| Rank | Metro | Annual sleep loss (hours/person) | Climate change impact (hours/person) | Share due to climate change |
| 1 | Chennai | 93 | 5 | 6% |
| 2 | Mumbai | 84 | 5 | 6% |
| 3 | Kolkata | 80 | 5 | 7% |
| 4 | Ahmedabad | 78 | 6 | 7% |
| 5 | Hyderabad | 75 | 7 | 9% |
| 6 | Bengaluru | 67 | 8 | 12% (Highest) |
| 7 | Delhi | 66 | 5 | 7% |
| 8 | Pune | 65 | 6 | 9% |
Sleep loss has doubled in five decades
The report highlights a worrying long-term trend. Across 1,335 of the 1,338 cities analysed worldwide, climate change-related sleep loss has at least doubled since the early 1970s.
Globally, the average person lost nearly 56 hours of sleep annually because of high nighttime temperatures during 2020-2025, with more than 10% of that loss directly linked to climate change. Researchers estimate that this is equivalent to losing nearly seven nights of sleep each year, including about one night due to climate change alone.
MUST READ: Zerodha's Nithin Kamath warns: 'India's poorest will be hit hardest by rising heat'
The report says nighttime temperatures are rising faster than daytime temperatures, while urban heat islands are trapping more heat after sunset, making cities especially vulnerable. Older adults, women and lower-income households without access to adequate cooling face the greatest risks. As climate change intensifies, researchers warn that reducing greenhouse gas emissions and improving access to cooling will be essential to protect public health and ensure people can get adequate sleep.
Climate change is increasingly disrupting not just weather patterns but also people's sleep. A new analysis by Climate Central has identified India as one of the global hotspots for climate-related sleep loss, with hotter nights causing residents in several states to lose dozens of hours of sleep every year. The findings show that while Chennai records the highest overall sleep loss among India's major metros, Bengaluru faces the strongest climate change-driven impact, underscoring how rising nighttime temperatures are becoming a growing public health concern.
The report analysed 1,338 cities globally and found that southern India experiences 78 to 91 hours of annual sleep loss, with 8 to 9 hours directly attributable to climate change. Researchers linked poor sleep caused by hotter nights to impaired cognitive performance, weaker immunity, cardiovascular disease, poorer mental health and reduced productivity.
Sleep loss hotspots
The study found that Puducherry recorded the highest overall sleep loss in India at 92 hours per person annually, followed by Andhra Pradesh (88.6 hours), Kerala (88.3 hours) and Tamil Nadu (84 hours). Gujarat (81.4 hours), Telangana (78.5 hours), Odisha (78 hours) and Chhattisgarh (77 hours) also ranked among the most affected states.
However, when researchers isolated the impact of climate change, Tamil Nadu topped the list, with residents losing an additional 7.9 hours of sleep every year because of global warming. Karnataka followed closely at 7.8 hours, while Rajasthan recorded 7 hours of climate-driven sleep loss. Maharashtra, despite having the largest representation in the study with 22 cities, recorded 76.3 hours of annual sleep loss, including 5.8 hours linked to climate change.
India's sleep map: States with the highest annual sleep loss (2020–2025)
| Rank | State/UT | Annual sleep loss (hours/person) | Sleep loss due to climate change (hours/person) |
| 1 | Puducherry | 92.0 | 5.0 |
| 2 | Andhra Pradesh | 88.6 | 5.8 |
| 3 | Kerala | 88.3 | 6.0 |
| 4 | Tamil Nadu | 84.0 | 7.9 |
| 5 | Gujarat | 81.4 | 5.6 |
| 6 | Telangana | 78.5 | 6.5 |
| 7 | Odisha | 78.0 | 5.3 |
| 8 | Chhattisgarh | 77.0 | 6.0 |
| 9 | Maharashtra | 76.3 | 5.8 |
| 10 | West Bengal | 75.0 | 5.6 |
Chennai and Bengaluru
Among India's eight major metropolitan cities, Chennai recorded the highest overall temperature-related sleep loss at 93 hours annually. Mumbai ranked second with 84 hours, followed by Kolkata at 80 hours.
Yet Bengaluru emerged as the city most affected by climate change. Residents lose an additional 8 hours of sleep each year because of climate change alone, the highest among India's metros. Nearly 12% of Bengaluru's total temperature-related sleep loss is now attributable to climate change.
MUST READ: Why Mumbai becomes a 'bathtub' every monsoon: Key factors behind the flooding
Hyderabad follows with 7 climate-driven hours of sleep loss annually, while Ahmedabad and Pune each record 6 hours. Although Delhi reports the lowest overall sleep loss among the major metros at 66 hours per year, climate change still accounts for 5 additional hours of lost sleep annually.
India's metro cities: Overall sleep loss vs climate change impact (2020–2025)
| Rank | Metro | Annual sleep loss (hours/person) | Climate change impact (hours/person) | Share due to climate change |
| 1 | Chennai | 93 | 5 | 6% |
| 2 | Mumbai | 84 | 5 | 6% |
| 3 | Kolkata | 80 | 5 | 7% |
| 4 | Ahmedabad | 78 | 6 | 7% |
| 5 | Hyderabad | 75 | 7 | 9% |
| 6 | Bengaluru | 67 | 8 | 12% (Highest) |
| 7 | Delhi | 66 | 5 | 7% |
| 8 | Pune | 65 | 6 | 9% |
Sleep loss has doubled in five decades
The report highlights a worrying long-term trend. Across 1,335 of the 1,338 cities analysed worldwide, climate change-related sleep loss has at least doubled since the early 1970s.
Globally, the average person lost nearly 56 hours of sleep annually because of high nighttime temperatures during 2020-2025, with more than 10% of that loss directly linked to climate change. Researchers estimate that this is equivalent to losing nearly seven nights of sleep each year, including about one night due to climate change alone.
MUST READ: Zerodha's Nithin Kamath warns: 'India's poorest will be hit hardest by rising heat'
The report says nighttime temperatures are rising faster than daytime temperatures, while urban heat islands are trapping more heat after sunset, making cities especially vulnerable. Older adults, women and lower-income households without access to adequate cooling face the greatest risks. As climate change intensifies, researchers warn that reducing greenhouse gas emissions and improving access to cooling will be essential to protect public health and ensure people can get adequate sleep.