Tokyo’s middle-aged commuters may be losing sleep over more than just work, researchers reveal that the farther and smaller you live, the worse your sleep gets.
Study: Commuting time, residential floor area, and their associations with insomnia and daytime sleepiness among residents of the Tokyo metropolitan area: a cross-sectional study. Image Credit: Urbanscape / Shutterstock.com
A recent study published in the Journal of Transport and Health examines the relationship between commute time and house area with insomnia and daytime sleepiness.
The commute-housing trade-off
Japan has the shortest mean sleep duration, less than 7.5 hours, among all developed countries. When stratified by age, adults between 40 and 50 sleep less than seven hours every night and report longer daily commutes.
Long-distance commuters are more likely to exercise less, be overweight, have high blood pressure, and experience poor sleep. These individuals frequently feel more tired, stressed, and less satisfied with their lives, in addition to being more likely to experience digestive disorders, musculoskeletal pain, and overall lower levels of wellbeing.
Living near the workplace often correlates with living close to or within the city. Residing in cities is not conducive to good sleep due to air, noise, and light pollution, in addition to the lack of green spaces and walkways, and a reduced sense of neighborhood and safe community.
In Japan, people frequently purchase their first homes in their 30s and rarely move houses thereafter. Thus, the choice of house among young adults may affect their sleep quality throughout their lives.
A larger multi-room house often allows the residents to escape from light and noise pollution, which is not possible in a small house with only one room. Conversely, living in a small house, typical of urban homes, may also disrupt sleep quality.
The disruptive effects of urban living and long commute times may work synergistically to worsen sleep quality. To date, no studies have comprehensively evaluated the combined effects of commute time and housing size.
About the study
The current study included 1,757 individuals between 40 and 59 years of age who responded to an online survey about their commute to workplaces in Tokyo. Validated scales were used to evaluate insomnia and daytime sleepiness, as well as dwelling size and daily commute time. The researchers also applied propensity score matching (PSM) to adjust for demographic and socioeconomic confounders such as age, sex, education, marital status, and household income.
Study findings
A total of 911 and 499 people reported insomnia and excessive daytime sleepiness, respectively. People who slept between seven and nine hours every night were 80% less likely to report insomnia or excessive daytime sleepiness. Similarly, people in their 50s were 20-25% less likely to report these conditions, respectively.
People who have longer commute times were more likely to experience insomnia and daytime sleepiness. For daily commute times of 100 minutes or more, the risk of insomnia and daytime sleepiness was 60% and 70% higher, respectively.
After adjusting for education, marital status, and household income, over 50 minutes of commute time was associated with a 22-35% increased risk of insomnia and daytime sleepiness.
People living in smaller houses or apartments were also more likely to have insomnia. People living in houses with a floor area of 115 square meters or more were 35% less likely to experience insomnia, whereas those who lived in houses with a floor area below 95 square meters were 44% more likely to have insomnia.
Each of these factors is independently responsible for insomnia and daytime sleepiness, irrespective of other potential demographic or socioeconomic confounding factors. The threshold appears to be living in a 95 square meter house while commuting 53 minutes to work, a value derived from a mathematical model rather than direct emperical observation.
Sleeping seven to nine hours every night is associated with the lowest risk of either insomnia or daytime sleepiness. However, this benefit is not observed in those who sleep more than nine hours every night, whose risk equals or exceeds that of those who sleep between five and seven hours.
A shorter commute time and higher housing floor area are predictors of better sleep quality and less daytime sleepiness, with effects appearing somewhat stronger among women, though this difference was not statistically significant. A larger house reduces the adverse impact of longer commutes, which may be attributed to greater life satisfaction and the ability to choose a house for maximum utility.
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Conclusions
Longer commute times are associated with a greater likelihood of insomnia and daytime sleepiness, while a small house floor area predicted insomnia but not daytime sleepiness.
Optimizing commuting time and housing size can help mitigate commuter-related insomnia.”
Journal reference:
- Matsushita, D., Xiong, X., & Wang, X. (2025). Commuting time, residential floor area, and their associations with insomnia and daytime sleepiness among residents of the Tokyo metropolitan area: a cross-sectional study. Journal of Transport & Health. doi:10.1016/j.jth.2025.102156.
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