When we think of heatwaves, we picture blazing afternoon suns. However, climate scientists and public health experts are increasingly warning about a stealthier, deadlier consequence of global warming: abnormally warm nights.
The Physiology of Nighttime Heat
The human body is designed to absorb heat during the day and release it at night when ambient temperatures drop. This nocturnal cooling is essential for physiological recovery. When nighttime temperatures remain high—especially above 30°C in Indian cities—the body is denied this recovery period. This continuous thermal stress severely taxes the cardiovascular system, leading to a spike in mortality, particularly among the elderly and outdoor workers.
The Urban Heat Island Multiplier
This crisis is magnified in cities by the Urban Heat Island (UHI) effect. Dense concrete buildings and asphalt roads absorb solar radiation all day and act like giant radiators at night, slowly releasing the trapped heat.
💡 Policy Imperatives
Public health policy must adapt. This requires mandating better building ventilation (passive cooling), expanding green cover and water bodies in cities, and providing subsidized, energy-efficient cooling solutions for low-income households who are most vulnerable to nocturnal heat stress.
