By Stephanie Gold, published on July 1, 2007 - last reviewed on September 21, 2011
You're under pressure. Deadlines are looming. Everyone is making demands on your time. Your anxiety level is rising. Your stomach is in knots. So you do what you've been well-trained to do. You make sure you get in your gym time.
But if neuroscientist Steven W. Porges is right, there's an even better way to counter stress. Exercise has its uses, but as a stress fighter it works primarily at a visceral level—and the operative word is fight. You're basically combating excess levels of cortisol, the hormone that spreads news of danger through your body and readies it to fight or flee.
You're better off working through higher—and more direct—channels, like the brain. The most efficient stress-reducer might just be a smile. Engaging socially with others triggers neural circuits that calm the heart, relax the gut, and switch off fear, Porges says.
The path from sociability to tranquillity is paved by the vagus nerve, the main route of the parasympathetic branch of the autonomic nervous system. The vagus wanders from brain stem to body, carrying signals to organs like the heart, lungs, and intestines, and regulating a number of facial muscles to boot. The vagus influences heart rate and breathing. It is intimately involved in how we perceive, react to, and recover from stress. When the vagus nerve is activated, heart rate slows, blood pressure drops, and the body enters a state of physical calm.
Over time, nature has elaborated a three-tier system of wiring to enable us to respond to immediate risk, says Porges, director of the Brain-Body Center at the University of Illinois.
All three are concerned with sorting out safety from danger, friend from foe. When we feel unsafe, we generally activate the fight-or-flight response, which conducts its business through the other half of the autonomic system, the sympathetic branch. Activation of sympathetic pathways is the physiological equivalent of pushing the panic button.
Older and more rudimentary among response strategies is total shutdown—freezing and immobilization. It's accomplished through an older version of the vagus nerve. So primitive is this vestigial channel, a holdover from our invertebrate past, that it lacks a protective coating of myelin, the fatty substance that sheathes most nerves in mammals, speeding the transmission of impulses.
Then there's the myelinated vagus, which serves as the pinnacle of our evolved capabilities. Linking the cranial nerves serving face, voice, and ears with the heart, lungs, and gut, it gives facial expressions and vocalizations privileged access to the circuitry modulating our visceral reactions. It is normally activated only under conditions of safety, but it provides the body with a much less taxing, and far more rewarding, escape from anxiety than fighting or fleeing.
When we scan our surroundings for risks, sweet smiles with gentle eye contact and soft voices with rhythmic inflections cue the brain structures that regulate the vagus nerve. The viscera lighten up: Heart rate slows, breathing eases. Stress switches off. You feel safe enough to move closer. Intimacy is now possible. Think of the vagus nerve as a social engagement system. And it works two ways. Social engagement creates the sense of safety that calms the viscera. And released from gut-wrenching anxiety, your insides now enable you to advance your social agenda, which further calms you.
Social interactions are very important in our experience as human beings, Porges says, and the social engagement system determines the quality of those interactions. Further, he calls the power of this system "amazing" both in terms of its effects on behavior and mental state and the speed with which it works. Not only do coping strategies like exercise tackle stress primarily at the visceral level, they actually work against deployment of the higher system. You may think exercise is curative, Porges says, but the calm you get from jogging 10 miles is more analgesic than therapeutic.
Exercise actually turns off the social engagement system by stimulating the sympathetic branch of the autonomic nervous system, which dampens the function of the vagus. Among its effects: blocking sensitivity to social cues. Distraction by some novelty may seem alluring at times of stress, but it bypasses the vagus nerve entirely and works at cross purposes to it. If your gut's in a knot, new and strange input will only aggravate the jitters. You're better off with old friends or favorite tunes than experimental sounds or the party where you don't know a soul. A skittish nervous system is really requesting familiarity and predictability, which is a metaphor for safety, Porges says.
Porges contends that our reaction to challenge is organized hierarchically, and that the evolutionarily newer neural circuits inhibit the older ones. We use the newer circuit to promote calm states, to soothe ourselves, and to engage with others. When this doesn't work, we mobilize for fight-or-flight behaviors. And if that doesn't do it, we resort to the old vagal system and freeze.
Our reaction to danger and the mobilization of defensive systems, rather than the engagement system, happens automatically, Porges observes. It's not a voluntary choice. It's as if our nervous system has betrayed us. But that doesn't mean we're stuck. "The mantra I use," Porges says, "is when your nervous system fails you, use behavior." To cope with such betrayals, we can learn to compensate—by moving into a quiet room or moving into social relationships rather than away from them.