The Effects of 24-hour Sleep Deprivation on the Exploration-Exploitation Trade-off.

Sleep deprivation has a complex set of neurological effects that go beyond a mere slowing of mental processes. While cognitive and perceptual impairments in sleep deprived individuals are widespread, some abilities remain intact. In an effort to characterize these effects, some have suggested an impairment of complex decision making ability despite intact ability to follow simple rules. To examine this trade-off, 24-hour total sleep deprived individuals performed two versions of a resource acquisition foraging task, one in which exploration is optimal (to succeed, abandon low value, high saliency options) and another in which exploitation is optimal (to succeed, refrain from switching between options). Sleep deprived subjects exhibited decreased performance on the exploitation task compared to non-sleep deprived controls, yet both groups exhibited increased performance on the exploratory task. These results speak to previous neuropsychological work on cognitive control.

The effects of sleep deprivation on information-integration categorization performance.

BACKGROUND: Sleep deprivation is a serious problem facing individuals in many critical societal roles. One of the most ubiquitous tasks facing individuals is categorization. Sleep deprivation is known to affect rule-based categorization in the classic Wisconsin Card Sorting Task, but, to date, information-integration categorization has not been examined. STUDY OBJECTIVES: To investigate the effects of sleep deprivation on information-integration category learning. DESIGN: Participants performed an information-integration categorization task twice, separated by a 24-hour period, with or without sleep between testing sessions. PARTICIPANTS: Twenty-one West Point cadets participated in the sleep-deprivation group and 28 West Point cadets participated in a control group. MEASUREMENTS AND RESULTS: Sleep deprivation led to an overall performance deficit during the second testing session-that is, whereas participants allowed to sleep showed a significant performance increase during the second testing session, sleepless participants showed a small (but nonsignificant) performance decline during the second testing session. Model-based analyses indicated that a major contributor to the sleep-deprivation effect was the poor second-session performance of a subgroup of sleep-deprived participants who shifted from optimal information-integration strategies at the end of the first session to less-optimal rule-based strategies at the start of the second session. Sleep-deprived participants who used information-integration strategies in both sessions showed no drop in performance in the second session, mirroring the behavior of control participants. CONCLUSIONS: The findings suggest that the neural systems underlying information-integration strategies are not strongly affected by sleep deprivation but, rather, that the use of an information-integration strategy in a task may require active inhibition of rule-based strategies, with this inhibitory process being vulnerable to the effects of sleep deprivation.

The effects of sleep deprivation on dissociable prototype learning systems.

BACKGROUND: The cognitive neural underpinnings of prototype learning are becoming clear. Evidence points to 2 different neural systems, depending on the learning parameters. A/not-A (AN) prototype learning is mediated by posterior brain regions that are involved in early perceptual learning, whereas A/B (AB) is mediated by frontal and medial temporal lobe regions. STUDY OBJECTIVES: To investigate the effects of sleep deprivation on AN and AB prototype learning and to use established prototype models to provide insights into the cognitive-processing locus of sleep-deprivation deficits. DESIGN: Participants performed an AN and an AB prototype learning task twice, separated by a 24-hour period, with or without sleep between testing sessions. PARTICIPANTS: Eighteen West Point cadets participated in the sleep-deprivation group, and 17 West Point cadets participated in a control group. MEASUREMENTS AND RESULTS: Sleep deprivation led to an AN, but not an AB, performance deficit. Prototype model analyses indicated that the AN deficit was due to changes in attentional focus and a decrease in confidence that is reflected in an increased bias to respond non-A. CONCLUSIONS: The findings suggest that AN, but not AB, prototype learning is affected by sleep deprivation. Prototype model analyses support the notion that the effect of sleep deprivation on AN is consistent with lapses in attentional focus that are more detrimental to AN than to AB. This finding adds to a growing body of work that suggests that different performance changes associated with sleep deprivation can be attributed to a common mechanism of changes in simple attention and vigilance.