The impact of urban transportation noise and bedroom temperatures on sleep quality during summertime

<p dir="ltr">Introduction: Heatwaves pose increasing risks to sleep health (Chevance et al., 2024), particularly in un-airconditioned apartments where high nighttime temperatures impair rest and thermal comfort. Equally, transportation noise, especially from road traffic, has been linked to sleep fragmentation and reduced sleep quality (Smith et al., 2022), yet its role in moderating heat-related sleep disturbances is not clear. This study integrated Department for Environment, Food and Rural Affairs strategic noise-map data (DEFRA, 2022) with continuous bedroom temperature logs and daily sleep-quality ratings, to understand whether road and rail noise independently predict the change in sleep quality experienced during UK summertime.</p><p dir="ltr">Materials and methods: The UK Home Heat Health project monitored bedroom climate and sleep in 123 healthy adults (mean age 35 years, 82 female) residing in un-airconditioned London apartments during June–September 2023–2024 (Lomas et al., 2024). Participants wore CamnTech actigraphs and completed a Consensus Sleep Diary with 10-point ratings of sleep quality, thermal comfort and heat-related sleep disturbance each day. Bedroom temperature was logged every 30 minutes via temperature sensors. External night-time noise (11 pm–7 am) for road and rail sources was extracted from DEFRA strategic noise maps (35 dB cutoff), categorised in 5 dB bands (reference < 35 dB). Noise levels are modelled on a 10-metre grid at a receptor height of 4m above ground. Each participant apartment was assigned a road noise level and rail noise level matching the exact location to the noise maps.</p><p dir="ltr">Analysis: A multiple linear regression modelled change in sleep quality scores (baseline – hot spell night) as a function of maximum bedroom temperature, road- and rail-noise, controlling for age and sex. A total of 119 participants with complete data and noise mapping were included in the analysis. </p><p dir="ltr">Results: A multiple regression was conducted to predict the change in sleep-quality score (baseline minus hot-spell night) from maximum bedroom temperature, road-noise bands, rail-noise bands, age group, and sex. The overall model approached significance, F(14, 104) = 1.75, p = .057, and accounted for 19.0 % of the variance in sleep-quality change (R² = .190; adjusted R² = .081). Examination of individual predictors showed that higher maximum bedroom temperature was associated with greater change in sleep quality, (p = .042). Among noise predictors, only the 65–70 dB road noise band significantly predicted change in sleep quality versus < 35 dB, ( p = .005) No other road- or railnoise bands, age, or sex reached significance (p > .05). </p><p dir="ltr">Conclusions: Although the model was only marginally significant, results indicate at possible interactive effects of overnight heat and traffic noise on sleep quality. These preliminary findings, based on noise-map estimates rather than direct measurements, highlight the importance of further research to clarify how thermal and acoustic stressors jointly influence sleep health in the context of urban apartments. Future studies should integrate primary noise monitoring, ventilation behaviour logs, and indoor climate data to explore these dynamics in depth.</p><p dir="ltr">Acknowledgments: We thank all the participants who took part in the Home Heat Health field trials of 2023 and 2024.</p>