It's not just hunger, blues, fatigue and mild dehydration that make us so tetchy. These little-known rage-enhancers can, too.
1. You Snacked on Microwave Popcorn
No matter what's irking you—your partner's tap-tap-tapping foot, a snarky comment, a printer jam—the wrong type of popcorn may play a role in turning annoyance into full-blown rage. Other culprits can include frozen pizza, crackers, canned frosting, coffee creamer…or anything else that contains high levels of trans-fatty acids (partially hydrogenated oils— see this list). There's a strong association between anger issues and the consumption of trans fats, claim researchers at the University of California at San Diego, who surveyed people's eating habits and moods. The theory is that trans fats may inhibit absorption of healthy omega-3 fats, which are known for tamping down hostile behaviors and making us feel calmer.
2. You Forgot Your Shades
On the sunniest days, we squint, and squinting makes us angry, explains Daniele Marzoli, PhD, a psychologist at Italy's University of Chieti-Pescara who tracked people's emotions when the sun was either in their face or to their back. (The upshot: Squinters reported feeling 44 percent more agitated and aggressive.) Problem is, your screwed-up expression—forehead furrowed, eyes narrowed, mouth twisted—is essentially a frown. And because mood and facial muscles are linked, your face signals to your brain that you're irritated (even if weren't…initially). To make matters worse, the tetchiness flares up almost instantly, Marzoli explains. Luckily, this one has a simple, fast-acting and potentially elegant remedy: sunglasses.
3. You Took It Standing Up
Or sitting down. Or in any other position in which you were vertical. Body posture affects emotions—and the neural activations associated with them, explains Eddie Harmon-Jones, PhD, a psychologist and an author of a study at Texas A&M University. When upright-positioned volunteers heard unfair, hurtful feedback about their personality and written work, their brain scans revealed more of a neural frenzy in a part of the brain associated with anger (the left prefrontal cortex), compared with those who heard the same criticism while lying on their backs or received neutral feedback while seated. Harmon-Jones recommends lying down (if possible) whenever irritation starts to bubble up. If your body is poised to lunge, you're going to react more strongly than if you're laid back (literally).
4. You Barely Lifted a Finger
The less you work out, the more you'll get worked-up (especially if you're already short-tempered), found a small, preliminary study led by exercise scientist Nathaniel Thom, PhD, then at the University of Georgia. Thom provoked high-strung male volunteers by showing them, for instance, photos of soldiers abusing kids and children starving. As a result, the men felt angry, and their brain activity reflected it. Those instructed to ride a stationary bike for a half-hour afterward, however, were more even-keeled during a second viewing (the images still upset them, but their anger didn't increase), while those who had rested reported feeling more enraged. The theory: Even moderate exercise may protect against a build-up of anger because it boosts levels of the soothing neurotransmitter serotonin…which puts us in a calmer, more constructive mind-set than lazing around all day.
5. You Read the Comments
Online rants and flame wars, though often entertaining, pose a problem: Innocent bystanders get burned. An experiment at the University of Wisconsin-Green Bay found that when people read fuming comments posted on websites (such as Justrage.com, “the internet anger sponge”), they inevitably felt more churlish and negative. Unfortunately, of all the emotions—joy, sadness and disgust included—it's anger that spreads fastest and most easily online, concluded Chinese researchers in a separate study that tracked 70 million tweets. That means if you read something explosive, chances are better than average that you'll not only feel the secondhand fury but also pass it on.
6. You're a Southpaw
Lefties and ambidextrous types get angrier—and not necessarily because scissors, spiral notebooks and slanted brooms are designed for righties—suggests a study led by Ruth Propper, PhD, a psychologist at Merrimack College. Propper and her colleagues observed that there was a greater difference in activity between the left and right hemispheres of the brain in non-right-handed people. And the greater the imbalance, the angrier people were, Propper claims. Which means, at least in theory, that an affront that wouldn't unsettle a righty might make a lefty seethe.