Influence of indoor air quality on sleep quality of university students in Lisbon

Sleep is a crucial aspect of the human daily life since it allows us to recover from physical and psychological fatigue and its lack can bring several consequences to human health. People spend around one third of their life sleeping but, despite that, their exposure to pollutants during sleep is often neglected. Specifically, students typically change their habits after entering university, due to the freedom that they are allowed at this stage of their lives. These habits often include their sleep patterns, which not only affects their health, but their academic performance as well. This study aimed to assess the indoor air quality (IAQ) that university students are exposed to in their sleeping environment and how it affects their sleep quality. Firstly, an online survey, based in standardized questionnaires, was conducted to a sample of 1040 individuals to characterize sleep habits and, ultimately, to provide an overview of the sleep quality of the Portuguese population. Students were one of the population groups that showed worse results: only 31% had good sleep quality and only 62% showed good sleep health. Afterwards, a study to assess sleep quality (by actigraphy and standardized questionnaires) and IAQ (by a monitoring unit based in low-cost sensors) during the sleeping period of two consecutive nights of 13 students in Lisbon university dorms was conducted. Mean levels of CO₂ and VOCs above the established legislation were found during sleep, indicating that ventilation conditions were not sufficient to keep an acceptable IAQ. Temperature was also out of the acceptable comfort range during 44% of the sleeping time. The perceived sleep quality of students was found to be negatively associated with the number of awakenings and the mean levels of carbon dioxide and relative humidity during the sleeping period. These results confirm previous findings where some IAQ parameters may influence the sleep quality of the individuals, highlighting the importance to focus on the IAQ of sleeping environments as a strategy to improve sleep quality of individuals.