Commuting and Depression: Are You a Rat on a Treadmill?
Back in the 1980s a scientist named Robert Sapolsky broke into the big time with eye-catching research on social stress in apes and monkeys. The papers themselves are dry and technical (see for yourself), but the gist is that the everyday stress of life at the bottom of the pecking order eventually builds up to the point that it recalibrates the brain’s stress-response machinery. That’s what chronic stress is—a disruption in normal daily cycles of hormones like cortisol that puts stressed-out monkeys (and people) at greater risk for all kinds of negative health outcomes, from heart disease to anxiety and depression.
From there, research on chronic stress took off, and scientists started to explore what parts of human life might affect us the same way being the runt of your troupe affects a baboon or macaque. Right near the top of that list is commuting. Ask anyone who’s ever spent 90 minutes in traffic on their local turnpike, and they’ll tell you that commuting, at its worst, is a boring, repetitive, slow, frustrating activity that takes away our sense of agency and makes us feel like cogs getting ground down by a vast smog-choked machine.
The traffic part is important: the health risks of commuting don’t affect folks whose trip to the office is a five-minute walk down a leafy sidewalk, or the work-from-homers who just need to stagger from bed to the couch. It also definitely doesn’t apply to “active commuting,” like biking to work.
In fact, some previous studies have found that the delay caused by traffic—not the actual length of your commute—is the biggest cause of long-term stress. Other factors are the loss of leisure time and the prolonged inactivity of sitting still for a couple hours every day, plus plain old boredom.
All together, long-term lengthy commuting adds up to a major hit to our mental health. It’s not just stress. Serious commuters also, on average, are less happy and less healthy in all kinds of ways.
Commuting and Depression
The formal name for the illness is major depressive disorder, or MDD. The important thing here is that depression, contrary to its popular image, is not just about how you feel. MDD is as real and physical as a heart attack, a disease whose primary mechanism is neurological: critical networks of neurons stop producing and absorbing the right amounts of key chemicals, making it harder to think, sleep, move, and feel. Here‘s the official definition, here’s a more useful everyday guide to what it looks like.
The exact symptoms of MDD vary from non-stop twitchiness to sleep problems, consistent exhaustion, an inability to concentrate, and the more emotional stuff we usually think off—feelings of worthlessness, sadness and hopelessness, and not finding joy in the things that usually make you happy. And it turns out that long commutes, especially behind the wheel, might be a major cause of all of them.
There’s been some limited research on this over the last few years. One was a study out of the UK where scientists found that the longer your commute is, and the more of it you do in a car, the more symptoms of depression you’re likely to have. Researchers in Beijing found that every extra 10 minutes of commute time increases your risk of clinical depression by just over 1%, which sounds small until you think about scale: if we added 10 minutes to the drive time of everyone commuting into New York City every day, 16,000 more people would develop major depression.
Breaking It Down
That brings us to the most recent study that’s worth talking about. The team worked out of South Korea, which they picked because it has both the longest commute times and the highest rates of depression out all the “developed” countries that make up the OECD. Basically, these countries are America’s economic peers. But where the US has an average commute time of just under half an hour, the average commute for South Koreans is over 50 minutes. Each way.
The study itself is one of those “all statistics all the time” kinds of studies where, instead of getting out on the street and collecting new data, the researchers snagged a huge Excel spreadsheet from the government (specifically, the Korean Working Condition Survey), picked out the data for the 23,415 people of working age who gave full info on their jobs, pay, and commute, and did a ton of statistical tests to look for patterns no one had seen before.
They organized responses into three categories: short (30 minutes or less), medium (31-59 minutes), and long (over an hour). Then they matched those numbers up with how each commuter scored on a simple-but-reliable test for depression called the WHO-5.
The big take-home result is that long commutes make you 16% more likely to report bad-enough symptoms that you qualify as depressed. That’s pretty close to the risk attached to experiencing a major traumatic event as a child.
Then there’s the breakdown. Men were more at risk if they:
- Were unmarried
- Had no children
- Had blue-collar jobs
- Had wages in the bottom 25%
- Lived in more rural areas outside of big cities
Photo by Renda Eko Riyadi
Interestingly, men who work standard 40-hour weeks seemed to be at higher risk than men with shorter hours or who work paid overtime. That may have to do with the indirect way that commuting causes depression: it’s not like getting into your car and merging onto the highway suddenly kills your attention span and sucks all the joy out of your favorite hobbies, it’s closer to that chronic stress effect that we mentioned at the beginning. Small stressors, building up over time, until your brain re-calibrates itself in a massively unhelpful way. Maybe working overtime means you get paid more, and that helps, whereas shorter hours make the commute matter less.
Whatever the exact mechanism, this is one of those studies where the little details matter less than the overall finding. Taking other research into account, the take-home message is that commuting has a cost, and it’s more than just time and money. Before you take a job that’s two hours down the freeway, be sure it’s a cost you’re willing to pay.
