수면 부족하면 '상황 판단능력' 현저히 떨어져 Research shows sleep loss impedes decision making in crisis

美 워싱턴대, 순간 판단 실험 진행

62시간 뜬 눈 참가자들, 테스트 하나도 못 맞춰

source news.wsu.edu

edited by kcontents 

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수면 시간이 부족하면 중요한 판단을 내려야 하는 순간에 판단 능력이 떨어질 수 있다는 연구 결과가 새로 나왔다.   폴 휘트니 미국 워싱턴대 심리학과 교수팀은 실험 참가자들의 수면 시간을 인위적으로 조절하면서 순간적인 판단 능력 평가를 수행한 결과 수면 시간이 부족한 경우 판단 능력이 크게 떨어진다는 사실을 밝혀내고 국제학술지 ‘수면’ 5월호에 게재했다.   체르노빌 원자력발전소 사고와 챌린저호 폭발 사건, 엑슨 발데즈호 기름유출 사건의 공통점은 수면 부족으로 인한 담당자의 부주의가 중요한 영향을 미쳤다는 점이다. 하지만 수면 부족과 긴급 상황시 판단 능력의 상관관계에 대한 연구는 그간 많이 이뤄지지 못했다. 수면 부족이 집중력을 떨어뜨린다는 정도의 연구가 대부분이었다.   연구진은 정보가 끊임없이 변하는 긴급한 상황의 특징을 최대한 반영할 수 있는 실험을 설계한 뒤 수면이 판단 능력에 미치는 영향력을 파악하는 실험을 실시했다.   우선 26명의 참가자들을 모집한 뒤 이들을 절반으로 나눠 호텔처럼 꾸며 놓은 실험실에서 생활하게 했다. 그 가운데 13명은 62시간 동안 잠을 못 자게 했고, 나머지 13명은 편안히 쉬도록 했다.   그런 다음 양쪽 참가자들에게 숫자를 한 쌍씩 연속적으로 보여주면서 1초 이내에 ‘go’와 ‘no go’로 지정된 숫자들을 판단하도록 했다. go와 no go는 각 숫자에 임의로 부여된 것으로 참가자들에게는 알려 주지 않았다. 참가자들은 go를 찾아낼 때마다 보상을 받았다.   연구진은 참가자들이 첫 번째 실험을 마친 뒤 잠시 휴식시간을 주고 다시 go를 찾아내는 실험을 했다. 하지만 이번에는 go에 해당하는 숫자를 바꿨다. 이전 실험에서 go에 해당하는 숫자를 기억하고 그걸 바탕으로 순간적으로 판단하는 참가자들을 혼란스럽게 만든 것이다.   실험 결과 잠을 못 잔 참가자들은 숫자쌍 40개에 대해 하나도 맞추지 못한 반면 충분히 쉰 참가자들은 최소 8개에서 최대 16개의 ‘go’를 찾아내는 데 성공했다.   반 돈젠 박사는 “수면 부족인 사람의 뇌는 급변하는 상황과 자신의 행동에 대한 피드백을 적절히 처리하지 못한다는 사실을 보여주는 것”이라고 말했다. 동아사이언스 최영준 기자 jxabbey@donga.com

Research shows sleep loss impedes decision making in crisis

By Will Ferguson, College of Arts & Sciences science writer SPOKANE, Wash. – The difference between life and death in the operating room, on the battlefield or during a police shootout often comes down to the ability to adapt to the unexpected. Sleep deprivation may make it difficult to do so, according to a Washington State University study published this month in the journal Sleep. For the first time, WSU researchers created a laboratory experiment that simulates how sleep loss affects critical aspects of decision making in high-stakes, real-world situations. Their results provide a new understanding of how going without sleep for long periods can lead doctors, first responders, military personnel and others in a crisis situation to make catastrophic decisions. Overcoming challenge of lab research Recent history is full of examples of the sometimes devastating consequences of people operating without enough sleep. Investigations into the Chernobyl nuclear power plant meltdown in Ukraine, the grounding of the Exxon Valdez oil tanker and the explosion of the space shuttle Challenger all concluded that sleep-deprived operators played a role in causing the accidents. A long-standing conundrum for sleep scientists has been creating a controlled lab situation that sufficiently simulates the circumstances leading to severe lapses in real-world judgment. Previous laboratory research consistently showed sleep loss degrades attention, but its effects on demanding tests of cognition like decision making appeared to be relatively small. “So there has been a disconnect between decision making in the lab where the effects of sleep loss appeared to be minimal and decision making in the real world where sleep loss can lead to big problems,” said Paul Whitney, WSU associate dean and professor of psychology. “Our goal was to bridge the gap and capture the essential elements of real-world decision making in a laboratory experiment.” Adapting to feedback crucial In a natural context, decision making is a dynamic process that requires a person to learn what is going on nearby as a result of his or her actions and changing circumstances. A surgeon, for instance, might notice a change in a patient’s vital signs midway through a procedure. The surgeon can then use this feedback decide a better course of action. Facilities at WSU’s Sleep and Performance Research Center allow for both scientific data collection and a restful night’s sleep.  “A novel aspect of this study was using a simple laboratory task that captures the essential aspect of real-world decision making of adapting to new information in a changing situation,” said John Hinson, professor of psychology. “Prior studies of sleep loss and decision making have not realized how important adapting to changing circumstances is in determining when sleep loss will lead to decision making failures.” Whitney, Hinson and Hans Van Dongen, director of the WSU Sleep and Performance Research Center at WSU Spokane, along with Melinda Jackson, now of the RMIT University, Victoria, Australia, recruited 26 healthy adults to take part in their study conducted at the Spokane sleep center. Thirteen of the participants were randomly selected to go 62 hours without sleep two days into the study while the other half of the group was allowed to rest. For six days and nights, the participants lived in a hotel-like laboratory where they performed a specially designed reversal learning task to test their ability to use feedback to guide future decisions. Mid-study switch confounds sleep deprived In the task, subjects were shown a series of numbers that, unknown to them, were pre-assigned to have either a “go” (response) or “no go” (non-response) value. They had less than a second to decide whether or not to respond to each number shown. Every time they correctly identified a number with a “go” value, they received a fictitious monetary reward. Errors resulted in a loss. After a while, both the sleep-deprived group and the controls started to catch on and selected the right numbers. Then the tricky part came. The researchers reversed the contingencies so that participants had to withhold a response to the “go” numbers and respond to the “no go” numbers. The switch confounded the sleep deprived participants. Even after being shown 40 numbers with reversed contingencies, they had almost zero success. On the other hand, the rested participants would catch on to the switch within 8-16 numbers. Implications of sleep-loss risk The data show that no matter how hard a person wants to make the right choice, sleep loss does something to the brain that simply prevents it from effectively using feedback. The study provides a new tool for investigating how sleep deprivation produces decision errors in real-life situations where information emerges over time. “People in high-stakes environments are held accountable for their actions when they are fatigued just like everyone else,” Van Dongen said. “However, we now know that when someone is sleep-deprived their brain simply can’t process feedback from their actions and changing circumstances. “Our findings tell us that putting sleep-deprived people in perilous environments is an inherently risky business and raises a number of medical, legal and financial implications,” he said. https://news.wsu.edu/2015/05/07/research-shows-sleep-loss-impedes-decision-making-in-crisis/

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