3 min readNew DelhiMay 18, 2026 06:00 PM IST
Heatwaves are often associated with harsh daytime temperatures, dehydration, and heat exhaustion outdoors. However, high temperatures at night can also pose serious health risks, especially when the body does not have enough time to cool down and recover. Nighttime heatwaves and high nighttime temperatures are increasingly becoming a serious public health concern.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
Unlike daytime heat exposure, nighttime heat often goes unnoticed, yet prolonged exposure to warm and poorly ventilated environments may place additional strain on the body, especially among older adults, children, pregnant women, and people living with chronic illnesses. To better understand this phenomenon and its effects on the human body, we spoke with an expert.
How does excessive heat at night affect the body differently?
Dr Palleti Siva Karthik Reddy, MBBS, MD general medicine, FAIG, consultant physician at Elite Care Clinic, tells indianexpress.com, “Excessive nighttime heat places a different kind of physiological stress on the body because it interferes with the body’s natural cooling and recovery mechanisms during sleep. Poor sleep quality caused by heat can elevate stress hormones, increase heart rate, and reduce cardiovascular recovery overnight.”
He adds, “People also tend to underestimate dehydration at night, as fluid loss through sweating continues even during sleep. Over consecutive days, this cumulative strain can lead to fatigue, irritability, headaches, poor concentration, and worsening of existing heart or respiratory conditions.”
Which groups of people are most vulnerable during nighttime heatwaves?
Dr Reddy mentions that older adults, infants, pregnant women, outdoor workers, and individuals with heart disease, diabetes, obesity, or respiratory illnesses are particularly vulnerable during nighttime heatwaves. Families should watch for symptoms such as excessive sweating, restlessness during sleep, rapid heartbeat, dizziness, confusion, muscle cramps, unusual fatigue, or reduced urine output.
In severe cases, he reveals that a person may develop heat exhaustion or heatstroke, which requires immediate medical attention. “Sleep disruption combined with persistent dehydration can quickly worsen underlying medical conditions in high-risk individuals.”
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Practical and affordable ways people can keep their bodies and homes cooler at night during a heatwave
Simple measures can significantly reduce heat stress at night, Dr Reddy mentions, even without air-conditioning. Keeping windows open during cooler late evening hours to improve cross ventilation, using cotton bedding and loose clothing, and avoiding heavy meals before bedtime can help regulate body temperature.
“Staying hydrated throughout the evening is equally important. In areas with unreliable electricity, people can use damp towels, earthen water pots, or cool water foot soaks before sleep to promote heat loss. Reducing indoor heat sources, such as unnecessary lights or cooking late at night, can also make sleeping spaces noticeably cooler,” concludes Dr Reddy.