The effects of bedroom air quality on sleep and next‐day performance

The effects of bedroom air quality on sleep and next‐day performance were examined in two field‐intervention experiments in single‐occupancy student dormitory rooms. The occupants, half of them women, could adjust an electric heater to maintain thermal comfort but they experienced two bedroom ventilation conditions, each maintained for 1 week, in balanced order. In the initial pilot experiment (N = 14), bedroom ventilation was changed by opening a window (the resulting average CO₂ level was 2585 or 660 ppm). In the second experiment (N = 16), an inaudible fan in the air intake vent was either disabled or operated whenever CO₂ levels exceeded 900 ppm (the resulting average CO₂ level was 2395 or 835 ppm). Bedroom air temperatures varied over a wide range but did not differ between ventilation conditions. Sleep was assessed from movement data recorded on wristwatch‐type actigraphs and subjects reported their perceptions and their well‐being each morning using online questionnaires. Two tests of next‐day mental performance were applied. Objectively measured sleep quality and the perceived freshness of bedroom air improved significantly when the CO₂ level was lower, as did next‐day reported sleepiness and ability to concentrate and the subjects' performance of a test of logical thinking.