Living in dormitories without air conditioning (AC) during a heat wave can lower students' ability to focus, harm their working memory and increase reaction times, a Harvard study has found.
The field study, the first to demonstrate the detrimental cognitive effects of indoor temperatures during a heat wave in a group of young healthy individuals, highlights the need for sustainable design solutions in mitigating the health impacts of extreme heat.
"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 heat waves," said Jose Guillermo Cedeno-Laurent, research fellow at Harvard University in the US.
"To address this blind spot, we studied healthy students living in dorms as a natural intervention during a heat wave in Boston," said Cedeno-Laurent, lead author of the study published in the journal PLOS Medicine.
Researchers tracked 44 students in their late teens and early 20s living in dorm rooms. Twenty-four of the students lived in adjacent six-story buildings that were built in the early 1990s and had central AC.
The remaining 20 students lived in low-rise buildings constructed between 1930 and 1950 that did not have AC.
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Researchers outfitted each student's 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.
The study was conducted over 12 consecutive days in the summer of 2016. The first five days consisted of seasonable temperatures, followed by a five-day-long heat wave, and then a two-day cool down. Each day the students took two cognition tests on their smartphones right after waking up.
The first test required students to correctly identify the colour of displayed words and was used to evaluate cognitive speed and inhibitory control - or the ability to focus on relevant stimuli when irrelevant stimuli are also present.
The second test consisted of basic arithmetic questions and was used to assess cognitive speed and working memory.
The findings showed that during the heat wave, students in the buildings without AC performed worse on the tests than students in the air-conditioned dormitories and experienced decreases across five measures of cognitive function, including reaction times and working memory.
During the heat wave, students in buildings without AC experienced 13.4 per cent longer reaction times on colour-word tests, and 13.3 per cent lower addition/subtraction test scores compared with students with air-conditioned rooms.
Combined, these data show that students in rooms with AC were not just faster in their responses, but also more accurate.