Dreamland: Adventures in the Strange Science of Sleep (11 page)

But the extra sleep wasn’t only about comfort. While technology has given the United States a distinct advantage in war, the human body has remained essentially the same. Our brains haven’t progressed at the same rate as our technology, which means that the computer on a nuclear submarine is taking orders from a solider whose mind is designed to hunt and gather. When an early human was sleep deprived, the greatest risk was that his prey would get away and he would have to return home empty-handed. Now, with weapons at a soldier’s fingertips that could literally destroy the world, the risk is much greater. But to lower the chance that even highly trained soldiers will make mistakes, the military had to understand exactly how sleep interacts with our ability to come to a reasonable conclusion.

If someone asked you why you decided to do something—put on a green shirt today instead of a blue one, become an accountant instead of a sailor, marry your college sweetheart instead of the dancer you met in a café in Barcelona—you could probably give an answer that combined some elements of emotion and reason. But for a long time, these dual tracks of decision making puzzled scientists trying to sort out the process of how we make choices amid the limitless options we are given in life. Plato, among the first to examine the way the brain arrives at a decision, likened the rational part of the brain to the driver of a chariot, and the rush of emotions that we experience to his horses. When impulsive feelings pulled against the brain, it was the job of the driver to rein them in and provide direction. “If the better elements of the mind which lead to order and philosophy prevail,” he wrote, “then we can lead a life here in happiness and harmony, masters of ourselves.” Letting our emotions take over, meanwhile, would result in ending up “like a fool into the world below.”

The concept that the mind was divided into an emotional and a rational half took hold in Western culture. Philosophers from Descartes onward noted the struggle between reason and feeling and envisioned a world in which logic kept us out of pain. While this philosophy was useful in telling us how we ought to think, it came with two problems. The first was that the chariot drivers of the mind were not doing the best job, because humans were not evolving into a coolly logical species. We continued to make choices that were not purely rational, leaving us much closer to the hot-tempered Captain Kirk than the emotionally detached Spock. Clearly, emotions play some kind of role in decision making or else we wouldn’t keep turning to them. Second, all of the theoretical ideas of how the mind balanced conflicting impulses didn’t address the way the brain literally worked.

Reason—which, along with the inclination to wear pants, is what separates us from our pets—had to come from somewhere. Scientists began the search for the spot in the brain responsible for rational thought. One decided to tackle the problem by cutting out parts of a monkey’s brain to see what happened. Monkeys that had their temporal lobe removed showed no fear or anger and tried to eat anything put in their mouths. From this, researchers realized that some small parts of the brain were responsible for higher thought and the regulation of emotion, and that damaging or removing them would drastically alter the way the brain perceived reality. For a monkey without a temporal lobe, everything looks like a banana.

The schematic design of the brain eventually became clear. A bean-shaped structure near the exact center of the brain called the thalamus lets us realize when we are sleepy, while its neighbor, the hypothalamus, monitors feelings of hunger and thirst. Groups of neurons about the size of almonds that are found near the ears, called the amygdala, are partly responsible for the formation of memories, especially those generated by an emotional experience. The nearby pituitary gland and adrenal cortex, meanwhile, send urgent messages in the form of hormones throughout the body when something frightens us.

What regulates all of the messages from the different parts of the brain is a mass right behind the forehead called the prefrontal cortex. Like a conductor in an orchestra, this part of the brain strives to hit the right balance between responses from the emotional parts of the brain and those from the areas responsible for higher thought. The outcome is a decision. The prefrontal cortex is working every waking second, directing attention in the supermarket, sustaining interest when balancing a checkbook, and suppressing any outward signs of frustration or anger. It notices patterns, and when something novel pops up, it goes to work assessing how new information gels with what the brain already knows. It is responsible for a wide range of decisions, both conscious and unconscious, from the recognition that the person walking toward the car is your brother to whether investing in a condo in Phoenix is a good idea.

Making decisions is a very taxing job, with no downtime. Unlike other parts of the brain, the prefrontal cortex gets no benefit from the time that the body spends in a relaxed environment. Even when you are swaying in a hammock sipping a cool beverage on a sunny afternoon, this part of the brain is constantly on alert, making sure you don’t topple over or spill your drink. While science still doesn’t know exactly how this happens, the time we spend in deep sleep is when the prefrontal cortex recovers and reboots for the next day’s work.

In 1999, Yvonne Harrison and James Horne, two professors at Loughborough University, an institution on the far outskirts of London, decided to test how sleep deprivation affects the ways the brain reacts to changing conditions. They developed a computer game that reflected the ebb and flow of the business world and found a number of MBA students to serve as test subjects. Just as they would in their future careers, each student was asked to promote sales of a hypothetical product until it achieved market dominance and profitability. Unbeknownst to them, the dynamics of the imagined marketplace changed halfway through the game once more competitors selling similar products appeared. Suddenly, strategies that used to work made sales plummet. Only students who recognized that they needed to change their strategy would be able to survive.

Harrison and Horne split the students into two groups. Those in the first group were able to sleep as much as they wished, while those in the second had their sleep restricted. Students who slept well watched their sales suffer when new competitors first entered their imagined marketplace, but most were able to recover quickly and adapt. Their counterparts didn’t fare nearly as well. After thirty-six hours, the sleep-deprived students were unable to cope with the unseen changes in the game. They continued to rely on what had worked before, not recognizing that these moves now cut into their bottom line. Soon, each was bankrupt. Without sleep, their brains lost the ability to consider any alternatives and became rigid in their logic. It was as if the mind’s conductor had forgotten the symphony and focused solely on the oboe, without noticing that something was amiss. Later brain scans showed that after as little as twenty-four hours without sleep, the neurons firing in the prefrontal cortex started to slow down, making it harder for us to complete a thought or see a problem in a new way.

That sleep deprivation makes the prefrontal cortex less adept at realizing the meaning of new information coming into the brain presents a problem when one is formulating a business strategy. Sometimes, however, new information takes a more threatening form, like the appearance of eight Japanese warships. That was the case just after midnight on August 9, 1942, when Allied troops were in the midst of their first major offensive battle in the Pacific theater during World War II. An invasion force of over eighty Allied ships had descended on Guadalcanal, a strategic outcrop of land about a thousand miles northeast of the tip of Australia. Marines had secured the island the day before, and the sailors manning the battleships ringing the island were on the lookout for a Japanese counterattack. Men on duty had been on antiaircraft watch—an alertness level just notches below full combat—for three straight days. They were exhausted, hungry, and sleep deprived.

The attack came just after one in the morning. Japanese battleships steamed toward the American fleet sitting near Savo Island, a speck of land twelve miles off the shore of Guadalcanal. The attack fleet ran head-on into the USS
Patterson
, which radioed a report of enemy ships approaching to the USS
Vincennes
and USS
Quincy
, two heavy cruisers not far away. The captain of the
Patterson
maneuvered his ship into position and gave the order to launch torpedoes, but the men below didn’t respond in time. The Japanese fleet sped by and then split into two. Twelve minutes later, one portion of the fleet caught the
Vincennes
and the
Quincy
off guard, despite the warning they had received from the
Patterson
. Meanwhile, the other group of Japanese ships pounced on the USS
Astoria
, another heavy cruiser. The ship’s captain woke up to the sound of the general alarm ringing and the rumble of cannon fire. Dazed and still thinking that any attack would come from the air, he ordered his men to cease firing out of fear that they were shooting at an Allied ship. It was a decision that cost lives.

The Japanese forces continued their assault and soon sunk the ship. Throughout the nighttime battle, four Allied ships were lost, killing more than a thousand men and leaving another seven hundred wounded. It was one of the most embarrassing defeats ever suffered by the U.S. Navy, and it generated a minor scandal. Military planners and politicians wanted to know how it was possible for the Japanese to sink so many Allied ships without much of a fight. After learning that he would be singled out in an unflattering navy report, the captain of one battered ship committed suicide.

Fifty years later, a navy psychologist named Nita Lewis Shattuck (formerly Miller) came across a description of the battle. A career military researcher, Shattuck had long studied human performance and the ways that the design of a ship workstation could affect sailors’ abilities to complete their tasks under stress. Ships had been updated since World War II, of course, but she hoped to find clues as to whether the layout of each ship contributed to the defeat. After reading only a few pages, she recognized that sleep deprivation played the biggest role that night in the Pacific. With so little sleep after days of combat and the need to maintain a constant state of readiness, the men aboard those ships simply weren’t able to react to an attack that came in an unexpected form. Their brains could not shift their cognitive framework from scouring the skies to patrolling the waters, missing the boats in plain view because they had their minds locked on the idea that enemy planes were the greater danger. To an overworked brain expecting an attack from the air, any ship on the water—even those firing at you—could not be the enemy. Like the MBA students who went bankrupt, the soldiers showed the signs of a prefrontal cortex that was exhausted and unable to respond to a situation that had changed.

The role of sleep in allowing the brain to adapt to new circumstances was noted in research studies well before it was fully understood. As early as 1959, the U.S. military noticed that the lack of sleep could severely undermine the discipline of troops going through routine chores. After keeping a group of soldiers awake for a couple of days, one military researcher noted, with the air of a disappointed parent, that “several participants passed through periods of giddiness and silly laughter, like addled drunks, when their behavior became uninhibited.”

In the early 1980s, the military began studying how specific tasks were affected by a lack of sleep. The results were troubling if you wanted to win a war. After a day and a half without sleep, air force bombers changed their vocal patterns, no longer enunciating or speaking loudly enough for their crewmates to always understand them. All of the nonverbal clues indicating that something was important—like raising one’s voice to suggest danger—vanished from their speech patterns. In another simulation, researchers separated pairs of soldiers into different rooms with a radio linkup between them. One soldier was given a featureless map with only a route and a destination drawn in, while his partner was given a map with all of the basic landmarks present but nothing in the way of directions. In order to get anywhere, the two would need to work together. The pairs made up of soldiers who had slept well completed the task with little problem. Those deprived of sleep for forty-eight hours were another story. The lack of sleep diminished their ability to communicate, effectively wiping out any sort of spontaneous dialogue—the running chatter that helps keep everyone focused on the same goal. It was rare for a pair of sleep-deprived soldiers to piece together a complete map, an essential communications task that soldiers who had slept well accomplished easily. The same breakdown occurred in another study that followed a crew of army soldiers operating on drastically reduced sleep during a simulated battle. Fighting exhaustion, they forgot to do critical tasks such as updating maps with new information and completing boring but important chores. The problems only worsened as the simulation progressed.

In every situation, the prefrontal cortex—the only part of the brain that has the power to think about how it is thinking—had lost the vital aspect of self-assessment, unable to tell if an action was helping to solve a problem or simply making it worse. Without sleep, the brain’s finely tuned mechanics had dissolved from an orchestra led by a conductor into a room full of musicians playing to their own beats. In a report warning that sleep deprivation could lead to mission failure, Shattuck argued that “the ability of sailors to think and reason while in a fatigued state has significant implications for combat effectiveness . . . [I]n such a scenario, sailors may give everything they have to give for the mission, but due to human physiology and as a result of fatigue brought on by sleep disruption, their best may not be good enough. The end result of a flotilla of sailors holding key operational positions, all operating in severe sleep debt, could be disastrous.”