Stop us if you've heard this one before: long commutes are bad for your health. Some of the strongest recent findings in behavioral science have focused on the perils of a long ride to work. People with a lengthy commute show an increased amount of stress, get worse sleep, and experience decreased social interaction. A commute of 45 minutes carries such a cost to well-being that economists have found you have to earn 20 percent more to make the trip worth it. Length alone isn't the source of the problem: stress rises with a commute's variability, and for transit riders it rises with the unpredictability and overcrowding of a bus or train.
Typically the negative health outcomes of commuting are studied independently. Recently a group of Swedish researchers decided to consider several of them at once. The team analyzed data from roughly 21,000 people in the Swedish province of Scania who worked more than 30 hours a week. (Most people there commute by car, though about a quarter get to work on public transit.) The participants reported their commute mode and one-way length, and answered several questions designed to assess their sleep quality, everyday stress, exhaustion, mental health, and general health.
Their findings, reported earlier this week in the journal BMC Public Health, are fully "in concordance with the findings of previous studies" [PDF]. Broadly speaking, a long commute corresponded with several negative health outcomes. Poor sleep quality, exhaustion, and low general health were linked most strongly with lengthy commutes, though stress was apparent as well. The only negative health connection the researchers failed to confirm was long commutes and low mental health.
Some of the study's more precise results are particularly intriguing. (It's important first to note the researchers divided commute lengths into just three groups: under 30 minutes, 30-60 minutes, over an hour.) For instance, the sleep quality, stress, and general health of transit users worsened as their commute length increased. But, interestingly, those outcomes were worse for drivers in the 30 to 60 minute range than in the hour-plus range. In other words, people who drove more than an hour to work slept better and were healthier, on average, than someone who drove 45 minutes.
At first glance this seems encouraging, but the researchers suggest it is a mirage of their particular population sample. In this part of Sweden most people driving about a half hour to work will be navigating city congestion. But those driving more than an hour are most likely heading to another part of the country along routes the researchers describe as "tranquil countryside driving." Some parts of that commute might even be relaxing. The researchers also raise the possibility of an additional explanation: the so-called "healthy commuter effect," which suggests that only people who are psychologically and physically fit enough to endure an hour-long drive to work actually stick to it over time.
One reason for the linear association among transit riders is most likely that longer transit rides often involve transfers. That not only increases the length of the trip but also its unpredictability (waiting for several different arrivals), its variability (some trips take much longer than others), and its potential for crowding — all factors that have been shown to increase the stress of the commute, as shown above.
But there was one truly hopeful result from the report (the only one noted by the researchers as "interesting"), and it came from workers who commuted less than 30 minutes by transit. If you fell into this group, your odds of having high everyday stress actually went down. Exactly why is anyone's guess — perhaps a quick subway hop is a good way to wind down — but, nevertheless, that's just one more reason mass transit might not be as bad as you think.