Commuting time, residential floor area, and their associations with insomnia and daytime sleepiness among residents of the Tokyo metropolitan area: a cross-sectional study

Abstract

Introduction: While urban residences offer advantages in commuting time, they are associated with a less favorable living environment than suburban residences. Understanding how housing location and size influence insomnia symptoms and daytime sleepiness can inform housing selection and supply strategies. This study examined whether commuting time and residential floor area predict insomnia and daytime sleepiness, whether these associations are attenuated by demographic/socioeconomic factors, and how commuting time and residential floor area are interrelated. Methods: In September 2024, we conducted an online survey involving 2000 employed individuals, aged 40–59 years, commuting to Tokyo workplaces, selected by stratified random sampling. Commuting time was calculated using a route search system based on home and workplace postal codes and commute modes. Insomnia and daytime sleepiness were assessed using the Athens Insomnia Scale (AIS) and Epworth Sleepiness Scale (ESS). Associations among sleep outcomes, commuting time, and demographic/socioeconomic factors were analyzed using bivariate logistic and multivariate linear regression with propensity score matching. Results: We analyzed 1757 valid responses. Even after adjusting for covariates, longer commuting times predicted insomnia and daytime sleepiness, whereas small residential floor area predicted insomnia. Shorter commutes improved sleep, suggesting a trade-off between commuting time and floor area. For a 95 m2 home, a 53-min commute was associated with exceeding the AIS insomnia cutoff. Conclusion: Reducing commuting time and optimizing housing location and size trade-offs may help mitigate commuter insomnia.