Biological Aging May Accelerate During a Heat Wave

New research suggests the damage from extreme heat does not necessarily end when the temperature drops.

You already know extreme heat wrecks your sleep and sends vulnerable people to emergency. A study published in July suggests the bill may not be settled when the weather breaks. It points to something researchers call biological aging, worth understanding before the next hot spell.

How does your biological age differ from your birthday?

Your chronological age is how many years you have been alive. Your biological age is a separate measure built from what your body is doing, using blood markers like cholesterol, inflammation and blood sugar control. Two people can both be 65 on paper while one has the internal function of someone years younger. When biological age runs ahead of the real one, researchers call that acceleration, and it tracks with higher risk of age-related disease.

What did the heat wave study actually find?

Researchers at Zhejiang University drew on the China Health and Retirement Longitudinal Study, following 2,318 adults aged 45 and over, and published their results in Cyborg and Bionic Systems. Over four years the average biological age climbed from 57.3 to 62.3, and just under 59 per cent showed acceleration at follow-up. Greater heat wave exposure was significantly associated with that gap widening, and effects were stronger in people with a higher body mass index, in cities, and in hotter southern regions.

Should you trust one study on extreme heat?

Carefully, and that is the authors' own position. Lead researcher Dengyong Xu notes the study is observational, so it shows a pattern but cannot prove extreme heat caused the aging. Jem Cheng, a human thermoregulatory physiologist and assistant professor at the University of British Columbia's Okanagan campus, was not involved but told CTV News the findings are concerning, since most of what we know about heat focuses on immediate dangers like heat illness and hospitalisations. In her view this is among the first evidence of lasting effects on the body's organ systems after the heat has passed.

Which habits for staying cool actually pay off this summer?

The advice does not change, but the stakes for following it might. Plan errands and exercise for cooler morning or evening hours, and drink water on a schedule rather than waiting for thirst. Without air conditioning, even a few hours in a mall, library or community cooling centre gives your body a real break, and staying cool with a cool shower or a damp cloth on the neck and wrists genuinely helps. Check on older neighbours. And if you take medication for blood pressure, heart conditions or mental health, know that some prescriptions change how your body handles heat.

What else do readers ask about heat waves?

Does a heat wave age your body for good?

The study found an association, not proof of permanent damage. It suggests repeated biological aging acceleration may accumulate in people exposed to more heat waves, which is different from saying one hot week ages you for good. The researchers are explicit that the design cannot establish cause, and that longer follow-up in other populations is needed.

Who faces the most risk in extreme heat?

Older adults, people living alone, people with heart, lung, kidney or mental health conditions, people taking certain medications, and anyone without access to cooling. In this study, effects were stronger among participants with a higher body mass index and those living in cities and hotter regions, which points to both health status and environment shaping vulnerability.

Which warning signs point to heat illness?

Heavy sweating, dizziness, nausea, headache, muscle cramps and unusual fatigue suggest heat exhaustion, and call for immediate cooling, shade and fluids. Confusion, very high body temperature, or skin that stops sweating can signal heat stroke, a medical emergency. Call 911 rather than waiting to see if it passes.

Prepare for the next hot stretch

Heat is no longer only a comfort issue. If you are unsure how hot weather interacts with your conditions or your prescriptions, find and book a pharmacist or walk-in clinic near you on Medimap, and the Health Hub has more on heat exhaustion symptoms and why summer dehydration creeps up on you.

General information, not medical advice. For heat stroke or any medical emergency, call 911. For non-urgent concerns, speak with a healthcare provider.