Last updated July 11, 2018 at 10:30 am
Study shows even the young and fit suffer cognitive decline in the heat.
Living in a hot dorm in a heatwave is more than just an unpleasant short-term problem. US researchers have discovered it can also have detrimental cognitive effects which, they say, highlights the need to design buildings that can cope with extreme heat in a world that’s getting hotter.
The study of students in their late teens and early 20s was the first to demonstrate the cognitive impact of heat on healthy young people.
“Most of the research on the health effects of heat has been done in vulnerable populations, such as the elderly, creating the perception that the general population is not at risk from heatwaves,” said lead author Jose Guillermo Cedeño-Laurent, from the Harvard TH Chan School of Public Health.
“To address this blind spot, we studied healthy students living in dorms as a natural intervention during a heatwave in Boston.”
Of the 44 students studied, 24 lived in adjacent six-storey buildings that were built in the early 1990s and had air-conditioning. The remaining 20 lived in low-rise buildings built between 1930 and 1950 and without AC.
Researchers fitted each room with a device that measured temperature, carbon dioxide levels, humidity and noise levels, and tracked their physical activity and sleep patterns with wearable devices over 12 consecutive days. The first five days were seasonable, followed by a five-day heatwave then a two-day cooldown.
Two daily cognition tests
Every day students took two cognition tests on their smartphones after waking up. The first required them to correctly identify the colour of displayed words and was used to evaluate cognitive speed and inhibitory control – the ability to focus on relevant stimuli when irrelevant stimuli are also present. The second consisted of basic arithmetic questions and was used to assess cognitive speed and working memory.
During the heatwave, students in the hot dorms performed around 13 per cent worse on both tests than those in the air-conditioned dorm and experienced decreases across five measures of cognitive function, including reaction times and working memory.
Students in air-conditioned rooms were faster and more accurate with their responses.
Interestingly, the most significant difference in cognitive function between the two groups was seen during the cooldown period, when outdoor temperatures began to subside but indoor temperatures remained elevated in the dorms without air conditioning.
“Indoor temperatures often continue to rise even after outdoor temperatures subside, giving the false impression that the hazard has passed, when in fact the indoor heatwave continues,” said Joseph Allen, co-director of the Center for Climate, Health and the Global Environment at Harvard Chan School.
“In regions of the world with predominantly cold climates, buildings were designed to retain heat. These buildings have a hard time shedding heat during hotter summer days created by the changing climate, giving rise to indoor heatwaves.”
The paper published in PLOS Medicine.