Hockenbury Discovering Psychology 5th txtbk

504 CHAPTER 12 Stress, Health, and CopingFigure 12.2 Disrupted Sleep: OneIndicator of Stress In the weeks immediatelyfollowing the 9/11 terroristattacks, the psychological stresscaused by those events was evident inthe increased sleep disruptions experiencedby millions of Americans. Evenyears after the attacks, many firefighters,police officers, and otherrescue and recovery workers continueto experience insomnia, recurringnightmares, and other sleep problems(Farfel & others, 2008; Stellman& others, 2008).Percent of American Adults Who Have Had SleepProblems Prior to and Following September 11Had difficulty falling asleep2001 until September 11 25%Following September 11, 2001Had frequent awakenings2001 until September 11Following September 11, 2001Wake up early and can't get back to sleep2001 until September 11 25%Following September 11, 2001Wake unrefreshed2001 until September 11Following September 11, 2001Source: National Sleep Foundation (2002).38%39%40%44%49%50%First, stress can indirectly affect aperson’s health by prompting behaviorsthat jeopardize physicalwell-being, such as not eating orsleeping properly (see Figure 12.2).For example, among residents ofManhattan, there was a sharp rise insubstance abuse during the weeksafter the September 11 attacks. Almost30 percent of residents participatingin a New York Academy ofMedicine survey reported that theyhad increased their level of alcoholconsumption, cigarette smoking, ormarijuana use (Vlahov & others,2002). High levels of stress can alsointerfere with cognitive abilities,such as attention, concentration,and memory (Mandler, 1993). Inturn, such cognitive disruptions canincrease the likelihood of accidentsand injuries.Second, stress can directly affect physical health by altering body functions, leadingto symptoms, illness, or disease (Kiecolt-Glaser & others, 2002). Here’s a very commonexample: When people are under a great deal of stress, their neck and head musclescan contract and tighten, resulting in stress-induced tension headaches. But exactlyhow do stressful events influence bodily processes, such as muscle contractions?Walter B. Cannon (1875–1945) Cannonmade many lasting contributions to psychology,including an influential theory ofemotion, which we discussed in Chapter 8.During World War I, Cannon’s research onthe effects of stress and trauma led him torecognize the central role of the adrenalglands in mobilizing the body’s resourcesin response to threatening circumstances—the essence of the fight-or-flight response.Cannon also coined the term homeostasis,which is the tendency of the body to main -tain a steady internal state (see page 320).Stress and the Endocrine SystemTo explain the connection between stress and health, researchers have focused onhow the nervous system, including the brain, interacts with two other importantbody systems: the endocrine and immune systems. We’ll first consider the role ofthe endocrine system in our response to stressful events and then look at the connectionsbetween stress and the immune system.Walter CannonStress and the Fight-or-Flight ResponseAny kind of immediate threat to your well-being is a stress-producing experiencethat triggers a cascade of changes in your body. As we’ve noted in previous chapters,this rapidly occurring chain of internal physical reactions is called the fight-orflightresponse. Collectively, these changes prepare us either to fight or to takeflight from an immediate threat.The fight-or-flight response was first described by American physiologist WalterCannon, one of the earliest contributors to stress research. Cannon (1932) foundthat the fight-or-flight response involved both the sympathetic nervous system andthe endocrine system (see Chapter 2).With the perception of a threat, the hypothalamus and lower brain structures activatethe sympathetic nervous system (see left side of Figure 12.3). The sympathetic nervoussystem stimulates the adrenal medulla to secrete hormones called catecholamines, includingadrenaline and noradrenaline. Circulating through the blood, catecholaminestrigger the rapid and intense bodily changes associated with the fight-or-flight response.Once the threat is removed, the high level of bodily arousal subsides gradually, usuallywithin about 20 to 60 minutes.As a short-term reaction, the fight-or-flight response helps ensure survival by swiftlymobilizing internal physical resources to defensively attack or flee an immediate threat.