Rising nighttime temperatures could cause people in southern India to lose up to 91 hours of sleep per year [1].
This projection highlights the growing intersection between environmental degradation and public health, as extreme heat transforms the domestic environment into a space where restorative rest is difficult to achieve.
Researchers conducted a study estimating that by the end of the 21st century, residents in southern Indian cities will face significant sleep disruptions [1, 2]. The study said Bengaluru and Chennai are areas where people are losing hours of sleep every year due to climate change [4].
While the total annual sleep loss across various cities is reported to range between 78 and 91 hours [3], not all of this loss is tied to global warming. The researchers said that approximately eight to nine hours of that annual loss are directly attributable to climate change [4].
Other regions of the country are also affected by the trend. Kolkata, for example, is reported to lose 80 hours of sleep annually due to rising night temperatures [5]. This puts the city among the third worst-hit locations in India, according to the study [5].
The disruption is driven by the increase in nighttime temperatures, which prevents the body from cooling down sufficiently to enter deep sleep. As the century progresses toward 2100, these thermal disruptions are expected to become more frequent and severe [1, 2].
“Southern India could lose up to 91 hours of sleep per year.”
The study suggests that climate change is no longer just an external environmental threat but a biological one that penetrates the home. By disrupting the circadian rhythm through nighttime heat, climate change may lead to long-term health complications associated with chronic sleep deprivation, potentially increasing the burden on India's public health infrastructure as temperatures rise toward the end of the century.
