The effects of bedroom air quality on sleep and next-day performance.
Level 2 - randomized trial
Individual randomized crossover field trials
PubMed 26452168 · doi:10.1111/ina.12254
What was done
Two balanced-order crossover field experiments were conducted in single-occupancy student dormitory rooms across two 1-week conditions. In experiment 1 (N = 14), ventilation was altered by opening a window (resulting in average CO2 concentrations of 2585 ppm versus 660 ppm). In experiment 2 (N = 16), ventilation was controlled via an inaudible fan in the air intake vent operating when CO2 exceeded 900 ppm (resulting in average CO2 concentrations of 2395 ppm versus 835 ppm). Participants adjusted electric heaters for thermal comfort; temperatures did not differ between conditions. Sleep was evaluated using wristwatch actigraphs, subjective morning questionnaires assessed air freshness and sleepiness, and next-day mental performance was tested.
What was found
Average CO2 levels were reduced from 2585 to 660 ppm in the first experiment and from 2395 to 835 ppm in the second experiment. The abstract reports that lower CO2 levels resulted in statistically significant improvements in objectively measured sleep quality, perceived freshness of bedroom air, next-day self-reported sleepiness, self-reported ability to concentrate, and performance on a test of logical thinking. Specific numerical effect sizes and p-values for sleep and cognitive outcomes were not reported in the abstract.
Why it matters
The study provides experimental field evidence that standard residential bedroom ventilation rates can directly affect objective sleep quality and next-day cognitive performance by moderating overnight indoor carbon dioxide accumulation.
Limits
Sample sizes were small (14 and 16 university students), limiting statistical power and generalizability to broader populations. The abstract does not provide exact numerical effect sizes, variance, or p-values for the sleep and cognitive endpoints. Other co-occurring indoor air quality parameters or environmental variables were not detailed.
Cited by
- supports Ambient carbon dioxide levels rising above 900 parts per million significantly impair sleep onset, sleep quality, next-day perceived fatigue, and next-day arithmetic ability.
- partial When bedroom carbon dioxide levels rise above 900 parts per million, it significantly impairs sleep onset, sleep quality, next-day perceived fatigue, and arithmetic performance.