Cooling for health: rising temperatures disrupt sleep, health and productivity

The rate of heat-related mortality has increased by 23% since the 1990s to 546,000 annually due to the increasing effects of climate change, according to the 2025 Global Report of the Lancet Countdown on health and climate change ^[1].

Rising temperatures represent a global public health crisis, affecting vulnerable age groups (infants <1 year and adults >65 years), reducing labour productivity and undermining various social determinants of health.

 

The Lancet reports that in 2024, rising night temperatures resulted in an increase of 9% in sleep loss from the 1986–2005 baseline, the largest percentage increase in lost sleep in the past decade ^[1]. Disrupting sleep health, elevated night-time temperatures are reported to alter sleep timing, quality, and quantity, subsequently impacting mental and physical health outcomes that are sensitive to sleep, such as cognitive function and cardiovascular disease.

 

According to a numerical study published in Nature, the global average sleep duration could be 16.37 hours shorter in 2100 than the annual average in 2001–2010 ^{[2, 3]}. Assuming no adaptation, and under a high-emissions climate change scenario (Shared Socieoeconomic Pathway 5–8.5), this would result in significant reduction in childhood IQ, along with an associated global economic cost of US$2.86 trillion in the 2100s.

 

Regarding labour capacity and productivity, the Lancet reports that, 640 billion potential work hours were lost globally due to heat exposure in 2024, exceeding the 1990–99 average by 98·1% ^[1].

 

Adaptation processes contribute to alleviate the detrimental health impact of rising temperatures, with air conditioning potentially saving 114 000 lives annually from heat-related deaths ^[1].

Adaptation strategies such as active or passive cooling measures can be included in Health National Adaptation Plans (HNAPs), which are essential policy mechanisms for integrating the health risks of climate change into national planning and decision-making processes.

 

 

Sources

[1] Romanello M, Walawender M, Hsu S et al. The 2025 report of the Lancet Countdown on health and climate change: climate change action offers a lifeline. The Lancet, 2025; 406, 2804-2857. https://doi.org/10.1016/S0140-6736(25)01919-1

[2] van Daalen, K.R., Ballester, J. Sleep loss in a warming world. Nat Sustain (2026). https://doi.org/10.1038/s41893-026-01778-y

[3] Chu, B. et al. Nat. Sustain (2026). https://doi.org/10.1038/s41893-026-01779-x