© Magnific
June 21, 2026
Marianne Waldenfels
Extreme heat may do more than strain the heart and circulatory system. Emerging research suggests that repeated heat waves could also accelerate biological aging. Here's what scientists know so far
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When people think about heat waves, most minds jump to circulatory problems, sleep deprivation, or dehydration. But new research suggests that extreme heat may also cause lasting changes in the body – including measurable effects on biological aging.
Two major studies now offer compelling evidence for this. The first, published in Nature Climate Change, analyzed data from 24,922 adults in Taiwan over a 15-year period. The second comes from the USC Leonard Davis School of Gerontology and was published in Science Advances. Both studies found a link between repeated heat exposure and accelerated biological aging.
The Taiwan study tracked participants from 2008 to 2022, combining health data with information on heat wave exposure. The focus was not on individual hot days, but on the cumulative burden built up over many years.
The long-term perspective is especially significant. The study shows that heat does not only have immediate effects, but can apparently trigger biological changes as well. This makes the findings particularly relevant for medicine.
The researchers measured a detectable increase in biological aging per interquartile range of multiple heat waves. The effect corresponded to between 0.023 and 0.031 additional years of aging. Notably, certain groups were more severely affected: people with physically demanding jobs, residents of rural areas, and those with limited access to air conditioning.
The second important study comes from the USA and was conducted by the USC Leonard Davis School of Gerontology. The researchers analyzed blood samples from more than 3,600 older adults aged 56 and above and examined epigenetic changes in the genome.
They compared this data with temperature maps of the entire United States and looked for correlations between biological age and the number of hot days at each person's place of residence. The result: people from regions with many extremely hot days show greater biological aging on average.
The numbers speak for themselves: for people from regions where temperatures reached at least 27°C for at least half the year, biological aging was accelerated by up to 14 months.
Every 10% increase in hot days extended molecular age by 0.12 years. People living in regions where the heat index reaches at least 32°C for half the year experienced up to 14 months more biological aging than those with fewer than 10 hot days per year.
Biologically, the connection is plausible. In extreme heat, the body must constantly work to maintain a stable core temperature. This demands energy and places strain on the circulatory system, metabolism, and cell functions.
One possible mechanism is oxidative stress. In this process, the body produces increased amounts of reactive molecules that can damage cells, proteins and DNA. When this stress occurs repeatedly, the body's own repair systems come under increasing strain.
There is also a chronic inflammatory response to consider. Repeated heat stress can push the body into a state where inflammatory processes remain persistently and slightly elevated — and it is exactly this kind of low-grade inflammation that is regarded as a key driver of biological aging.
Also Sleep also plays a role. Warm nights impair recovery, increase strain on the circulatory system, and shorten the time the body has to regenerate. During prolonged heat waves in particular, these effects can accumulate.
Both studies are compelling, but should not be taken as definitive proof of causation. They establish a link between heat waves and biological aging, though not yet an ironclad cause-and-effect relationship. This is typical in environmental medicine, where controlled long-term experiments involving extreme heat are simply not feasible.
This is precisely why large cohort studies are so important. They reflect real-world living conditions and allow us to draw conclusions about long-term health burdens. The fact that the Taiwan study followed nearly 25,000 people over 15 years, while the US study included more than 3,600 adults from across the entire country, makes their findings particularly significant.
The agreement between the two studies is particularly striking. Two independent cohorts from different geographic regions show similar effects, which makes the evidence considerably more robust.
Those who cannot simply avoid the heat are at particular risk — including outdoor workers, people in physically demanding jobs, and residents of regions with inadequate heat protection infrastructure.
Older adults and people with cardiovascular disease, diabetes, or kidney problems are also especially vulnerable. In these cases, heat can more rapidly lead to dehydration, blood pressure issues, and strain on the circulatory system.
There is another concern as well: poor nighttime sleep impairs recovery. A lack of nighttime cooling is therefore not merely uncomfortable — it has genuine medical implications. The longer this disruption to recovery persists, the greater the cumulative toll on the body.
General advice like "drink plenty of fluids" only goes so far. What actually helps are concrete measures that reduce the real heat burden.
Whether heat directly accelerates aging has yet to be conclusively proven. Even so, the existing data offers compelling indications that repeated heat stress could have long-term effects on biological health. With heat waves becoming increasingly frequent and intense, prevention is therefore more important than ever.
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