Sleep and indoor air quality: an exploratory polysomnographic evaluation of potential associations

This exploratory pilot study examines the potential impact of indoor environmental exposures on sleep quality, with a particular focus on a comprehensive characterization of indoor air quality (IAQ) parameters and their association with sleep architecture assessed through polysomnography. The study was conducted during the cold seasons of 2016 and 2017 with a small sample of 10 subjects from the urban area of Lisbon, Portugal. Polysomnography was performed over two consecutive weeknights, while IAQ monitoring took place over three consecutive nights using typical real-time instruments. Additionally, bioburden was assessed in each bedroom before and after the sleep period using active methods. The analysis was based on correlations between the environmental parameters and the sleep data from these 10 subjects. Parametric and non-parametric statistics were employed to examine potential associations, with a significance level set at α = 0.05. The findings showed that higher bedroom temperatures during sleep were associated with a decrease in REM sleep. Both minimum and mean heart rates (HR) increased with higher levels of CO and CO₂, while post-sleep bacteria levels were linked to a decrease in maximum HR. Fungal levels in the bedrooms were associated with a reduction in NREM2, and higher formaldehyde exposure was found to increase REM sleep latency. Exposure to PM_2.5 negatively impacted NREM1, RDI, and snoring, while PM₁₀ levels were negatively correlated with WASO and RDI. Although these findings provide a preliminary baseline, they are based on a small sample and may not be representative, highlighting the need for future studies to confirm the effects of various IAQ parameters on sleep quality in a larger and more diverse population.