In a laboratory, it’s extremely difficult to study why some people are better at bouncing back than others because it’s so hard to simulate the real stresses and strains of life. Scientists can show people scary pictures or movies to trigger their reactions and measure how they recover, but it’s hardly the same as a mugger in an alley or a grizzly bear on a hiking trail. Dr. Andy Morgan of Yale Medical School set out to find a real-world laboratory where he could watch people under incredible stress in reasonably controlled conditions.
He ended up in southeastern North Carolina at Fort Bragg, home of the Army’s elite Airborne and Special Forces. This is where the Army’s renowned survival school is located. It’s also where they believe in something called stress inoculation. Like vaccines, a small challenge or dose of a virus in your system prepares and defends you against a bigger challenge. In other words, they expose you to pressure and suffering in training so you’ll build up your immunity. It’s a kind of classic psychological conditioning: the more shocks to your system, the more you’re able to withstand.
The toughest part of the 19-day training takes place in a secret location at Camp Mackall called the Resistance Training Laboratory. Translation: a mock prisoner-of-war camp where students have the chance to put into practice what they have learned in the classroom phases of survival school. Everything is modeled on real enemy encampments, including guard towers, razor-wire fences, concrete cells and metal cages. It’s even got fake graves marked with crosses to scare you. The goal is to simulate hell on earth like the Hanoi Hilton in Vietnam or Al Qaeda’s torture chambers. If they allow you to use the latrine, they make you relieve yourself in a hole in the ground like some do in the Third World. The camp itself is off-limits to outsiders, and what really goes on behind the concertina wire is strictly classified. I’m told by several people who have gone through this program that highly trained professionals serve as jailers and interrogators who put the prisoners through a kind of carefully choreographed chaos designed to disorient them and break them down.
While they’re frightening you and wearing you down with sleep deprivation, blaring music and semistarvation, they’re also interrogating you using enemy techniques copied from World War II, Korea and Vietnam. They claim that they don’t use torture, but the sessions are known to be very rough.
For Morgan, POW school was the perfect place to study who survives the best under acute stress. If you think it’s just training and the soldiers know they’re not really in serious danger, consider what Morgan discovered. During mock interrogations, the prisoners’ heart rates skyrocket to more than 170 beats per minute for more than half an hour, even though they aren’t engaging in any physical activity. Meanwhile, their bodies pump more stress hormones than the amounts actually measured in aviators landing on aircraft carriers, troops awaiting ambushes in Vietnam, skydivers taking the plunge or patients awaiting major surgery. The levels of stress hormones are sufficient to turn off the immune system and to produce a catabolic state, in which the body begins to break down and feed on itself. The average weight loss in three days is 22 pounds.
Morgan’s research—the first of its kind—produced some fascinating findings about who does the best job resisting the interrogators and who stays focused and clearheaded despite the uncontrollable fear. Morgan looked at two different groups going through this training: regular Army troops like infantrymen, and elite Special Forces soldiers, who are known to be especially “stress hardy” or cool under pressure. At the start or base line, the two groups were essentially the same, but once the stress began, and afterward, there were significant differences. Specifically, the two groups released very different amounts of a chemical in the brain called neuropeptide Y. NPY is an abundant amino acid in our bodies that helps regulate our blood pressure, appetite, learning and memory. It also works as a natural tranquilizer, controlling anxiety and buffering the effects of stress hormones like norepenephrine, one of the chemicals that most of us simply call adrenaline. In essence, NPY is one of the fire hoses that your brain uses to extinguish your alarm and fear responses by keeping the frontal-lobe parts of your brain working longer under stress.
Morgan found one very specific reason that Special Forces are superior survivors: they produce significantly greater levels of NPY compared with regular troops. In addition, 24 hours after completing survival training, Special Forces soldiers returned to their original levels of NPY while regular soldiers were significantly below normal.
With so much more NPY in their systems, the Special Forces soldiers were much more clearheaded under interrogation stress and performed better according to the trainers. Special Forces soldiers really are special and different from the rest of the Army. They stay more focused and engaged in a crisis and bounce back faster afterward because their bodies produce massive amounts of natural anti-anxiety chemicals. In the fog of war—and everyday life for that matter—that’s a major advantage.
At the elite Navy Diving and Salvage Training Center in Panama City, Fla., they know how to figure out quickly who will be capable of accomplishing extremely dangerous underwater missions. They take young sailors and tie their hands behind their backs and bind their feet. They put the strap of a dive mask between the sailors’ teeth and then throw them in the Olympic-size pool. The challenge is to stay afloat and live. “The more someone struggles,” Morgan tells me, “the harder it is to get air and the more tired they get. You just have to inhibit the powerful, incredible instinct to breathe and your anxiety and alarm.” Morgan knows how scary it is because they also tied him up and threw him in so he could understand what the sailors were going through. Most trainees quickly realize that the only way to avoid drowning is to relax and sink to the bottom of the pool, kick off powerfully toward the surface, gasp for a little bit of air through clenched teeth and then fall back into the water and drop down to the bottom again.
During this testing, a lot of sailors black out. They simply don’t get enough oxygen and lose consciousness. Morgan has watched many of them sink to the bottom of the pool before divers pull them to the surface. On the deck, the unconscious sailors are rolled on their sides, and as soon as they revive, an instructor shouts again and again: “Are you gonna quit? Are you gonna quit?” Sailors are given 30 seconds to answer or they’re kicked out of the program. If they say they want to keep going, they’re given another 30 seconds to recover and then they’re thrown back into the pool. It may sound sadistic, but the Navy is simply trying to identify who will survive the most dangerous missions and who won’t. Through this grueling test, it finds soldiers and sailors who refuse to give up, who can suppress the need to breathe, who trust that they’ll be rescued if something goes wrong and who are prepared to lose consciousness—or even die—following orders.
In another arduous test, sailors are taken three miles off the Gulf Coast at night and are given a target destination on the beach. Dumped in the water, the students submerge and are not allowed to surface until they reach their objective. To make the challenge even more stressful, a clock is running and the divers aren’t allowed to go deeper than 25 feet. Despite the tides and currents, they’re also forbidden to swim parallel to the beach looking for their target. The penalty for breaking any of the rules is immediate expulsion from the course. Speed, efficiency and accuracy are a critical part of their grade.
In this underwater navigation test as well as the exercise in the pool, Morgan found again that brain chemistry makes a big difference. The amount of NPY you pump is closely connected to your success—the more, the better. Morgan also found that the best underwater navigators release a lot of a natural steroid called DHEA, which buffers the effects of the stress hormone cortisol and helps the brain’s hippocampus with spatial relationships and memory. Divers with the most NPY and DHEA graduated at the top of the class. Those with the lowest amounts did poorly.
At POW camp and dive school, Morgan has discovered a simple and accurate way of predicting who will survive and perform the best under extreme stress. You might call it the telltale heart. It starts with something called heart-rate variability, or HRV, the variations between beats. Healthy people have a lot of variability in the intervals between their beats, with their tickers speeding up and slowing down all the time.
It turns out that the best survivors don’t have a lot of heart-rate variability. Instead, they’ve got “metronomic heartbeats”—their hearts thump steadily like metronomes—with almost no variability between beats. That is, the intervals between the beats are evenly spaced. Morgan believes that a metronomic heartbeat is an easy way to detect good survivors and high neuropeptide Y releasers. It makes sense biologically because your brainstem, which controls your heartbeat, has a high density of neuropeptide Y.
Morgan analyzed the heartbeats of soldiers and sailors before they experienced major stress. Sure enough, the ones with metronomic heartbeats performed the best in survival school and underwater navigation testing. They also did the best in what’s called close-quarters combat training. Morgan analyzed their heart rates right before they went into mock battle. They were all suited up in combat gear, waiting for a buzzer to ring that would send them running into a building to “kill” the enemy and rescue hostages. (They use “simunitions,” simulated ammunition that hurts but doesn’t cause real harm.) The ones with metronomic heartbeats, Morgan says, shoot more bad guys and kill fewer hostages. Unfortunately, this metronomic effect is usually associated with early heart disease and even sudden death. Morgan wonders whether the same thing that makes you really good at surviving under high stress may not translate into excellent heart health when you’re 50. Without it, though, these elite forces might never even make it that far.