The temperature crosses 45 degrees during the day and rises up to 5 degrees Celsius even at night. This is not a dry report of the Meteorological Department, but the terrible truth of this year which has taken away both the sleep and health of crores of Indians. In the last week of April 2026, the minimum night temperature was recorded 5 degrees Celsius above normal in more than 17 cities of the country. This increase is not just a figure, but it is proving to be a ‘silent killer’ for the human body. Let us understand what this ‘rising heat of the night’ is, how it is breaking the body and why the situation is going to become more frightening in the coming days…
What does it mean if the night temperature rises by 5 degrees?
When we talk about ‘night temperature increasing by 5 degrees’, it means that after the end of the day the mercury is much higher than normal. For example, the night temperature in Delhi during April 2026 remained consistently above the 2020-2025 average and the 1991-2020 normal level. On April 29, it increased to 28.5 degrees Celsius. At the same time, the minimum temperature at night in Hyderabad remained stable at 28.8 degrees Celsius, which was 2 degrees more than normal.
This is called ‘warm nights’ or ‘hot nights’. For scientists, this is a situation when the temperature at night is so high that the body does not get a chance to recover from the heat of the day. This situation is no longer limited to May-June only, but has started appearing in April itself.
What happens to the body when the nights are hot?
Actually, the human body has been designed like a natural cooling system. After the intense heat of the day, the cool temperature of the night brings the body’s core temperature back to normal, providing rest and recovery to our body parts. But when the night temperature remains between 28-30 degrees Celsius, this natural process completely collapses. A study even suggests that if the night temperature goes above 30 degrees Celsius, the death rate can increase by 265%.
Understand its effect on the body like this:
- Direct hit on heart and mind: Continuously hot nights increase the risk of heart diseases and stroke manifold. According to reports, on days when there are hot nights, the risk of death is 50% higher than on normal nights.
- Attack of diseases: Hot nights not only cause heat stroke but also seriously aggravate non-communicable diseases like diabetes and hypertension.
- Disintegration of mental health: Poor sleep due to heat weakens the immune system, impairs concentration, increases fatigue and has a very bad effect on mental health.
AC-coolers are also failing, why can’t you sleep?
The root cause of all this is sleep deprivation. Cooling of the body is very important for our sleep. A study in Chennai found that the temperature inside houses of middle and lower middle class remained above 32 degrees Celsius at night. In some cases it reached 35 degrees Celsius. Walls and ceilings absorb heat during the day and radiate it at night, due to which fans and coolers become ineffective. In a controlled study it was also found that increasing night temperature increases the core body temperature during sleep, due to which sleep remains shallow and incomplete.
Why are cities burning like a frying pan?
Senior environmentalist Dr. Professor Subhash C. Pandey believes that this problem is even more serious in cities, which is due to the ‘urban heat island effect’. Concrete, roads, bricks and metal in cities absorb heat throughout the day and release it at night. Lack of greenery, depletion of water bodies and crowd of tall buildings further add to this heat. 93% of the districts fall in the category of extreme or high heat risk. A major reason for this is the formation of urban heat islands.
Will the situation worsen further in the coming days?
The heat wave is not going to stop here. According to a climate assessment, the hottest day temperature in India may rise by 4.7 degrees Celsius by the end of this century, while the coldest night temperature may jump by 5.5 degrees Celsius. That means, the nights will heat up faster than the days. This can be gauged from the fact that in 83% of the world’s big cities, the night temperature is continuously rising to dangerous levels.
This picture is scary, but this danger can be reduced by adopting some easy measures:
- Stay hydrated: Keep drinking enough water and electrolyte liquids not only during the day but also in the evening and night.
- Try to keep the house cool: Keep curtains on the windows during the day so that the heat does not come inside. Create cross-ventilation of air at night. If possible, use ‘cool roof’ technology on roofs.
- Change your sleeping pattern: Sleep wearing light cotton clothes. Use cotton sheets on bed. Do not eat heavy food before sleeping.
- Special care for weak people: The elderly, children, pregnant women and people with pre-existing medical conditions are most sensitive to hot nights. In such a situation, there is a need to pay special attention to the health of these family members.
- Administrative Initiative: The government and urban planning institutions will also have to include monitoring of night temperatures and measures to deal with it in the heat action plan. Till now most of the schemes focus only on the heat of the day. Increasing greenery in cities, reviving ponds and creating ventilation corridors are very important steps for the future.
After all, how big is this crisis?
Dr. Subhash C Pandey says, ‘This is not a small problem. 57% of the country has come under high heat risk zone, where 76% of the country’s population lives. More than 70% of districts experienced five or more extra hot nights per summer season between 2012 and 2022. This is a nationwide health crisis which is gradually deepening.
Rising temperature at night is no longer just a matter of discomfort, but has become a deadly health risk. When the body does not get relief at night, it is not ready to bear the heat of the next day, and this cycle keeps breaking us a little bit from within every day. At present, the biggest protection is to understand the impact this silent killer is having on our sleep and health and taking measures to avoid it.
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