Urban Heat Island effect is making your nights hotter and you sick. Here is how you can mitigate its effects

North and central India are in the grips of an intense heatwave with daytime temperatures pushing past the 44°C mark. This extreme heat is not even sparing urban air-conditioned bedrooms at night. Thousands of people are complaining of waking up exhausted, battling morning headaches, fatigue, and brain fog. Heatwaves are interfering with the body's natural sleep mechanisms, causing people to wake up several times at night, which prevents them from entering REM sleep. The body needs to cool down for a good night's sleep. However, experts say that prolonged exposure to extreme daytime heat, combined with unusually warm nights, is affecting this considerably. An extreme cool setting on the AC is making things worse. The effects are being seen most in people suffering from asthma, obstructive sleep apnea, allergic airway diseases, cardiovascular conditions, and dehydration.

What is happening inside homes at night?

Reports suggest that India’s nights are warming nearly five times faster than its days. According to the India Meteorological Department (IMD) data, overnight minimum temperatures are significantly above normal. A study by Climate Trends in May 2026 revealed that indoor nighttime temperatures in dense urban homes frequently hover between 31°C and 34°C, and do not go down even in the wee hours of the morning. This creates a "Warm Night" crisis, where our bedrooms act like structural heat traps. Sleeping in such conditions has a major effect on people's health.

Also Read: IMD predicts early monsoon arrival as severe heatwave scorches North and Central India

Why does heat persist outside even at night?

Earth follows a natural cooling cycle where it absorbs solar energy during the day and then throws the heat back at night. But this is no longer happening effectively. The Urban Heat Island (UHI) effect is to blame for this. Reinforced cement concrete (RCC), asphalt, and glass have filled the Indian cities. Due to their high thermal mass, these materials absorb immense heat all day and slowly radiate it outward for hours after dark. This is known as the Urban Heat Island (UHI) effect. Your air-conditioner creates a vicious cycle by adding more heat to the environment. It pumps it outdoors, but with millions of more ACs running at the same time, the hot exhaust being released by the compressors increases evening temperatures by an additional 4°C to 6°C. The humidity makes things worse as the moisture in the air disrupts the body's primary cooling mechanism, sweat evaporation.

Also Read: Delhi Heatwave: Capital reports first severe heatstroke case this summer, youth hospitalised in RML Hospital

How is your body suffering from extreme heat at night

Studies have shown that your core body temperature must drop by about 1°C for deep sleep. But with indoor temperatures remaining above 30 degrees Celsius at night, your body struggles to make this happen. Your heart goes into overdrive and starts pumping faster to push blood to your skin to shed heat. This causes the person to wake up several times at night. In the absence of REM sleep, the body does not get the opportunity to recuperate from daytime heat. You wake up tired, complaining of morning headaches, and this can cause long-term cardiovascular strain.

Also Read: Delhi sizzles at 45.1°C amid yellow alert; intense heatwave grips north and central India

How to cool your room and body without drying the air

Here are some things you can try to make indoor conditions better at night

1. Do not open your doors and windows at 6 pm. Do this instead at 9 pm when the outside air temperature has dropped. Open windows on opposite sides of the room to create a functional cross-breeze.

2. Fans are simply moving hot air around. Placing a bowl of ice or a damp, cold sheet directly under the fan will lead to evaporative cooling, instantly bringing down the temperature by a few degrees. In air-conditioned rooms, place a bucket of water to add moisture to the air to prevent dehydration.

3. While a cold shower might sound like a good idea, it is not. It causes your blood vessels to constrict rapidly, trapping heat inside your core. Take a lukewarm shower before sleeping. It opens your pores and blood vessels, allowing your body to efficiently dump internal heat.

4. Consume electrolytes in the evening instead of plain water. ORS, salted buttermilk and coconut water are good options to maintain blood volume and lower your resting heart rate while you sleep.

5. Painting the ceiling with reflective cool-roof paint or white lime wash can drop indoor ceiling temperatures by a massive 2 degrees C to 4 degrees C.