This research adds to the existing evidence on the detrimental effects of heat in different ways on different segments of the population. This study of students is the first to observe the effects of no air conditioning during a heat wave on the cognitive function of young and healthy people.

Study Parameters

Researchers at the Harvard T.H. Chan School of public health observed 44 university students—24 resided in dorms with air conditioning and 20 lived in dorms without—over 12 days during July 2016. Five days of the trial were conducted before the heat wave, five days during the heat wave, and two days after the heat wave.

During the 12 days, the students took self-administered cognitive tests every morning after waking and completed survey questions to report how well rested and hydrated they were. Participants also wore sleep-tracking devices that measured the quality of their sleep. In addition, the researchers assessed the indoor air quality of each participant’s bedroom.

Heat Hurts the Brain

The students living in dorm rooms without air conditioning performed worse on cognitive tests as the temperature spiked compared to their baselines scores and the scores of the group staying in air-conditioned dorm rooms.

The high indoor temperatures combined with environmental factors such as poor ventilation and increased noise due to open windows and fans, and behavioral ones such as lack of sleep and dehydration negatively affected the students’ performance.

Since the researchers measured the effects of temperature immediately after the students woke up, they can’t say whether the findings would extend throughout the day.

A Hot and Bothered Future

The researchers noted that because of its design, the dorm buildings retained heat after the heat wave, and only cooled down through air conditioning.

They stress that future buildings should be designed to release heat and to lessen the dependence on air condition, which contributes to global warming, uses too much energy, and raises the risk of indoor pollution.

Heat and More Vulnerable Populations

This study observed young, healthy students; the researchers assume heat negatively effects other groups of people more significantly, and noted that further research was warranted.