In Tokyo, scientists have found that the longer you commute and the smaller your home, the more likely you are to struggle with insomnia.
The study highlights a powerful urban trade-off: the convenience of city living versus the deep rest our bodies need. Smarter housing and commuting solutions could be key to improving sleep health in crowded cities.
Sleep Struggles in Modern Life
Roughly one-third of a person’s life is spent asleep, yet between 30 and 40 percent of adults experience insomnia at some point. In Japan, the problem is especially pronounced: people there sleep the least among all member nations of the Organization for Economic Co-operation and Development (OECD), averaging about one hour less than the group’s overall average.
Studies in public health have shown that long commuting times, along with constant noise and light pollution in densely populated areas, can interfere with healthy sleep. While living in the city often means shorter trips to work, urban housing tends to offer less comfort and quiet than suburban life. To better understand how location and home size affect rest, researchers in urban architecture are now exploring a key question: “Where and what size home should one have for better sleep?”
Investigating Sleep and City Life
To explore this issue, Professor Daisuke Matsushita and his team at Osaka Metropolitan University’s Graduate School of Human Life and Ecology analyzed how commuting time and housing conditions relate to insomnia and daytime fatigue among people living in the Tokyo metropolitan area.
Using an online survey with stratified random sampling, the researchers estimated each participant’s commuting time through a route search system based on their transportation method and the postal codes of their home and workplace. Levels of insomnia and daytime sleepiness were measured using the Athens Insomnia Scale and the Epworth Sleepiness Scale. The team also determined whether these patterns held true after accounting for demographic and socioeconomic differences.
Findings: Commute, Home Size, and Insomnia
Data analysis revealed that even after adjusting for covariates, longer commutes predicted insomnia and daytime sleepiness, while smaller housing size predicted insomnia. Further, a trade-off was observed between commuting time and floor area in cases of insomnia. For housing units meeting the urban-oriented residential area standard of 95 m² for a four-person household, commuting times exceeding 52 minutes reached the insomnia cutoff value.
“Housing choices and supply that consider the trade-off between location and size may help improve the sleep health of commuters and reduce sleep-related economic losses in metropolitan areas,” said Professor Matsushita.
The findings were published in the Journal of Transport and Health.
Reference: “Commuting time, residential floor area, and their associations with insomnia and daytime sleepiness among residents of the Tokyo metropolitan area: a cross-sectional study” by Daisuke Matsushita, Xiao Xiong and Xiaorui Wang, 29 August 2025, Journal of Transport & Health.
DOI: 10.1016/j.jth.2025.102156
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