Suffocation, dread and exhaustion: How extreme heat takes a toll on the body and the mind

When the daytime air feels like an oven and night brings no relief, people in Karachi, Pakistan, say the heat “goes straight to the head”. They mean more than dizziness or sweat.

It’s the creeping panic of a body that cannot cool down: restless nights, frayed tempers, a household on edge. Here, a heatwave is not simply a matter of high temperatures. It’s a public health emergency that seeps into every corner of life: physical health, sleep, mood and the invisible care work that keeps families and neighbours alive.

Our research in Pakistan and Kenya (Karachi, Lahore and Nairobi), shows how extreme heat affects local communities.

For families living on informal and unstable incomes and in fragile housing, such heat is not just uncomfortable; it can be deadly.

Heatwaves occur when temperatures push daily highs past 40 degrees celsius inland and above 35 degrees celsius on the coast. In 2015, a single heatwave killed more than 1,200 people in Karachi during just one week in June. But the quieter psychological toll which is rarely counted in official statistics builds with every wave of extreme heat.

In our research, residents describe lying awake in stagnant air, waking drenched in sweat and starting the next day already exhausted. Sleeplessness makes emotions harder to manage, fuelling...

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