Among various environmental factors, CO2 concentration during sleep affects sleep quality. In this study, we investigated the effects of natural ventilation using windows and room-side openings on indoor air quality and women’s sleep. An in-home experiment was conducted with 10 healthy women in their 20s under three ventilation conditions: closed room, open window, and open door. Sleep was monitored using a portable electroencephalograph, and environmental parameters such as temperature and CO2 concentration were continuously recorded. Window ventilation significantly reduced CO2 concentrations and resulted in higher sleep efficiency than the other conditions. These findings suggest that short periods of natural ventilation, particularly window ventilation, can improve both indoor air quality and sleep quality. This indicates the potential of non-mechanical interventions to improve sleep environments, particularly for young women.
Akemi Iwaki (2026) studied this question.