Heat islands, sleepless nights and a public challenge

📌 Summary:

• Context: a US-based climate group's study of 1,300+ cities found the average person lost ~56 hours of sleep annually (2020–2025) to unusually high night-time temperatures — at least 10% of it directly attributable to climate change
• India's big cities lose far more than the global average: Chennai 93 hours, Mumbai 84 hours, Delhi 67 hours
• Core argument: sleep is wrongly treated as an individual lifestyle problem — when the environment makes rest impossible, sleep becomes a PUBLIC HEALTH challenge
• Causal chain: longer/hotter/more humid summers + the urban heat-island effect (dense settlements retain heat at night) raise night temperatures → disrupted sleep; compounded by screen time, social-media addiction, erratic eating and shift work
• Health cost: sleep is vital for cellular repair, immunity and inflammation control; chronic deprivation is linked to hypertension, diabetes, heart disease, obesity and cognitive impairment, and cuts productivity while raising accident risk
• Solutions proposed: heat action plans must cover dangerously warm NIGHTS (not just daytime), especially in dense urban areas; better urban planning, affordable cooling, improved housing design; integrate sleep health into public-health campaigns as part of tackling non-communicable diseases

🎯 UPSC Relevance: GS3 — climate change impacts and urban heat islands; GS1/GS2 — urbanisation and public health governance

📝 Prelims Facts:

• Study covered 1,300+ cities; ~56 hours average annual sleep lost (2020–2025), 10%+ attributable to climate change
• Indian city sleep loss: Chennai 93 hrs, Mumbai 84 hrs, Delhi 67 hrs
• Urban Heat Island effect: dense built-up areas stay warmer, especially at night

🔑 Key Term: Urban Heat Island (UHI) — the phenomenon where dense urban areas are significantly warmer than surrounding rural areas, especially at night, due to heat-retaining surfaces