Your commute isn't just annoying; it's killing you. View Full Caption Thinkstock/Mike Watson Images

We've all griped about the stalled trains, closed stations and crowded cars that make us seethe with indignation and fantasize about living anywhere else but here.

And we'll continue to complain, with good reason: New Yorkers commute an average of 6 hours and 18 minutes per week, longer than workers in any of the nation's other 29 largest cities, according to a 2015 report by city Comptroller Scott Stringer.

The toll our daily commute takes on us has long-term implications on our mental and physical health, research shows.

Here's what researchers like Richard Wener, a professor of environmental psychology at NYU and longtime tri-state commuter, have taught us:

1. Commuting can raise our cortisol levels, which is definitely not a good thing.

In a 2004 study of suburban rail commuters taking the train from New Jersey to Manhattan, Wener and his co-author Gary Evans found that the longer their test subjects' journey was, the higher the levels of cortisol (the primary stress hormone) in their saliva, and the more difficult they found to focus on the task of proofreading assigned them at the end of their commute.

Invasions of personal space had an affect on cortisol levels, too, Wener and Evans concluded in a follow-up paper.

"What our data showed was...that crowding made a difference, although the measure that was important wasn't how many people were in the car," Wener explained. "It was the likelihood that somebody was bumping into you."

Chronic stress and overexposure to cortisol — which increases sugars in your bloodstream, alters your immune system responses, suppresses your digestive and reproductive systems, and communicates with that part of your brain that controls mood, motivation and fear — puts you at risk for mental health problems like anxiety and depression, and a whole host of physical health issues.

2. Having to make transfers during our commutes raises our stress levels.

Wener and Evans' research also supported the theory that the fewer transfers a commuter has, and the easier they are, the less stressed he is.

That's because transfers add an element of unpredictability to our travels.

"Everybody who's ever ridden a train system knows this intuitively: Every time you have to transfer, that reduces your predictability," Wener said, and each unexpected missed connection adds on to your projected travel time.

Waiting for subways and buses is particularly exasperating when we have no idea how long the delay will be. That's why the MTA's countdown clocks, while often inaccurate, can provide such relief: They cancel out the stress of uncertainty.

"You're sitting there and not wondering if the next train will be in 20 minutes," said Wener, who had hoped to test the clocks' effects on straphangers' stress levels. "You can look at it and see pretty much what's happening."

3. Long commutes are shown to reduce how much we sleep and exercise.

Each minute spent commuting translates into a 0.2205 minute sleep time reduction, according to 2009 study based on data from the American Time Use survey. If you commute an hour each way, you're losing 26.5 minutes of sleep each day and 2.2 hours a week.

One third of Long Island Rail Road commuters surveyed in 1999 complained of "at least moderate difficulty falling or staying asleep," and another third reported "at least moderate difficulty staying awake" during the day. Those with long commutes, of greater than 75 minutes, said they slept an average of 97 minutes longer on weekends than weekdays; they also napped more en route than commuters with trips 45 minutes long or shorter.

4. Ninety-minute commutes are correlated with high cholesterol and BMI.

Nationwide, one in three employees commuting more than 90 minutes, surveyed by the Gallup-Healthways Well-Being Index in 2010, said they had experienced recurrent neck and back pain in the past 12 months. Only one in four with commutes of 10 minutes or less complained of the same symptoms.

Employees with lengthy commutes were more likely to report a diagnosis of high cholesterol and a body mass index that categorized them as obese, the report said.

That's in part because the time we spend on the subway or the road is time we aren't using to exercise or prepare food at home: each minute devoted to commuting correlates to a 0.0257-minute reduction in exercise time and a 0.0387-minute reduction in food preparation time, the 2009 study found.

Those who commute long distances are also more likely to buy food at restaurants, not grocery stores, and engage in less strenuous exercise.

The stresses of commuting are also associated—surprise, surprise!—with elevated blood pressure levels.

5. All that travel back and forth to work makes us lonely.

According to Harvard political scientist Robert Putnam, the author of a best-selling book about the disintegration of American civic life, commuting is a strong predictor of social isolation.

“There’s a simple rule of thumb: Every 10 minutes of commuting results in 10 percent fewer social connections," he told the New Yorker in 2007. "Commuting is connected to social isolation, which causes unhappiness.”

6. Commuting might even make us more likely to divorce our spouses.

After sifting through 10 years of records for 2 million Swedes, Umea University's Erika Sandow found in 2011 that married and unmarried co-habitating couples were 40 percent more likely to divorce if one partner was commuting for longer than 45 minutes each day.

The risk of a break-up decreased after five years of long commuting, as families adapted to a routine that kept them apart and assigned more household responsibilities to the stay-at-home partner.

7. Those with the longest commutes could actually be shaving years off their lives.

Looking at data from Statistics Sweden covering the period from 1985 to 2008, Sandow and her colleagues at Umea also found a statistically significant link between commutes longer than 31 miles one way and an earlier death for women with low incomes or limited education. The lengthier the commute, the stronger the correlation.

At a 2013 meeting of the Association of American Geographers, Sandow said her team couldn't explain why commuting disproportionately affected women's life spans, but she suggested that women's greater household obligations made limitations on their time at home more stressful.