Overview
- Dense cities are recording unusually high overnight minima and indoor night temperatures often in the low 30s°C, preventing the normal roughly 1–1.5°C drop in core body temperature needed for deep sleep.
- Doctors at AIIMS and hospitals warn this night-time heat causes repeated awakenings, shallow sleep and a cumulative 'heat burden' that worsens concentration, mood and immunity.
- Night heat increases overnight sweating and electrolyte loss, leaving people — especially the elderly, children and those on diuretics — prone to dehydration and higher resting heart rates.
- Practical, low-cost measures widely recommended by sleep specialists and GPs include pre-cooling rooms, drawing curtains during the day, timed cross-ventilation, lukewarm showers, breathable bedding and using fans with evaporative cooling tricks.
- Experts and studies point to urban heat island effects and heat expelled by many air conditioners as the main drivers that keep nights hot, meaning long-term relief will require urban planning and building changes such as reflective roofs and more green cover.