Why a siesta could help us adapt to extreme heat

The siesta has been around for millennia, but in western countries like Spain it has been disappearing, mainly to conform to a "normal" 9-to-5 work schedule.

But the ferocious heatwaves in Europe over the past few weeks, worsened by climate change, have led even the Germans to consider using it as a tool to help manage hot weather.

There have been a few scientific attempts to gauge whether an afternoon nap is good for your health or not. Some studies say yes, some no, but the limited research all comes from wealthy countries where a siesta means a rest in a nice, cool bedroom all to yourself.

I've recently completed a study with Warumungu Elder Norman Frank Jupurrurla and ANU Academic Associate Professor Aparna Lal, published today in Lancet Planetary Health, examining the association between hot weather and deaths over the last 40 years in Australia's Northern Territory. The findings suggest that white people are sitting in aircon for way too long, de-acclimatising at their peril.

Over the past 40 years, non-Indigenous people have prospered in the Territory and now live an average of 15 years longer as a result. In the 1980s, houses were simple and made to catch the breeze. Few were air-conditioned. Nowadays every room inside a newly built mansion is permanently set at 21 degrees. But prosperity has done nothing to protect against heat. In fact, Territorians are becoming more vulnerable to heat over time despite these extraordinary gains in health and wealth.

It's not just the architecture that has dramatically changed - so too has the lifestyle. Non-Indigenous people spend most of the hottest parts of the year inside with the aircon blasting. Not socialising or exercising, but watching Netflix under a blanket and eating ice-cream from the freezer.

But for Aboriginal people, living in the heat goes hand-in-hand with everyday life, ancestry and more recently over the last century, poverty. Rich in a culture deeply shaped by the environment, Aboriginal people have been completely excluded from the Territory's newfound prosperity. The remote housing crisis is extreme - not only are air conditioners a luxury, so too are refrigerators. Compared to the 15 years of life gained for non-Indigenous people, Aboriginal Territorians have gained just one extra year over the same period. It is the housing crisis that drives illnesses like rheumatic heart and kidney disease that deepens the chasm between Indigenous and non-Indigenous life expectancy.

Yet despite the profound housing and wealth inequities in the NT, our study found that Aboriginal Territorians are no more vulnerable to heat-related deaths - and are perhaps even less so - than their non-Indigenous neighbours.

So why are Aboriginal people in the Northern Territory so remarkably resilient to extreme heat?

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To put it simply, Aboriginal people are protected by a culture that accepts and lives within the constraints of the climate, whereas non-Indigenous people tend to fight the heat or withdraw completely into air-conditioned homes and offices. Non-Indigenous people now live as if it was a perfect 21 degrees Celsius all year round. We're less active, less social and, as our study suggests, less able to cope with hot weather.

In fact, aircon may be part of the problem. Living in air conditioned space dampens bodily acclimatisation that optimises how we sweat, how blood flows to the skin, how our kidneys filter and even how hard our hearts beat.

Our study shows that we have a lot to learn about how to live better lives in hot climates. Last year I rode my pushbike home from work early one baking tropical afternoon past a group of Aboriginal people sitting quietly under a shady tree. On the opposite side of the road was a team of red-faced white men in hardhats screwing sheets of iron onto a roof. I imagined the blokes on the roof having animosity towards these "lazy" Aboriginal people and also imagined the Aboriginal people thinking "white people really are warunga (crazy)".

As I rode by, sweat pouring down my face, I made eye contact with one of the group. He had a whimsical look on his face and I am sure I saw his lips make the word "warunga" in my direction.

Technology and endless air con is not going to save us from climate change, but cultural change might - if we're willing to listen.