745Sleep Deprivation and Decision Making-Whitney et al.
INTRODUCTIONThe effect of sleep deprivation on cognitive performance is not uniform. 1 In laboratory studies, sleep deprivation has consistently been shown to substantially degrade vigilance and sustained attention, whereas its effects on demanding tests of complex cognition such as decision making appear to be inconsistent and relatively small. 2,3 Paradoxically, in the natural environment there are well-documented deficits in decision making due to sleep deprivation. 4,5 In emergency response, disaster management, military encounters, and other fast-paced situations with uncertain outcomes and imperfect information, good decision making is significantly hampered by sleep deprivation.
6-8Although the lapses of sustained attention that are characteristic of sleep deprivation contribute to errors and accidents, 3,8 attentional lapses are not the whole story of sleep deprivation effects on naturalistic decision making. The laboratory tasks often used to examine sleep deprivation effects on decisions typically do not include elements of updating information over Study Objectives: To better understand the sometimes catastrophic effects of sleep loss on naturalistic decision making, we investigated effects of sleep deprivation on decision making in a reversal learning paradigm requiring acquisition and updating of information based on outcome feedback. Design: Subjects were randomized to a sleep deprivation or control condition, with performance testing at baseline, after 2 nights of total sleep deprivation (or rested control), and following 2 nights of recovery sleep. Subjects performed a decision task involving initial learning of go and no go response sets followed by unannounced reversal of contingencies, requiring use of outcome feedback for decisions. A working memory scanning task and psychomotor vigilance test were also administered. Setting: Six consecutive days and nights in a controlled laboratory environment with continuous behavioral monitoring. Subjects: Twenty-six subjects (22-40 y of age; 10 women). Interventions: Thirteen subjects were randomized to a 62-h total sleep deprivation condition; the others were controls. Results: Unlike controls, sleep deprived subjects had difficulty with initial learning of go and no go stimuli sets and had profound impairment adapting to reversal. Skin conductance responses to outcome feedback were diminished, indicating blunted affective reactions to feedback accompanying sleep deprivation. Working memory scanning performance was not significantly affected by sleep deprivation. And although sleep deprived subjects showed expected attentional lapses, these could not account for impairments in reversal learning decision making. Conclusions: Sleep deprivation is particularly problematic for decision making involving uncertainty and unexpected change. Blunted reactions to feedback while sleep deprived underlie failures to adapt to uncertainty and changing contingencies. Thus, an error may register, but with diminishe...