Sleep deprivation adversely affects interpersonal responses to frustration

Sleep deprivation produces negative effects on mood and cognitive function, but existing data have almost exclusively utilized objective rating scales, which do not permit evaluation of idiosyncratic and unstructured responses. In this study, we used a semi-projective measure, the Rosenzweig Picture-Frustration (P-F) Study, to assess subjective responses to frustration following two nights without sleep. Twenty-six healthy volunteers completed the P-F at rested baseline and again following 55 h of continuous wakefulness. Participants provided written responses for an ambiguous cartoon character confronted with various frustrating situations. Relative to rested baseline, sleep deprivation was associated with altered responses on several indices, indicating a great number of uncommon types of responses, increased tendency to blame others for problems, and a reduced willingness to alleviate a conflict situation by accepting blame. Individual differences in several aspects of emotional intelligence were predictive of the extent to which responses to frustration changed with sleep loss. These findings suggest that sleep deprivation significantly weakens the inhibition of aggression and willingness to behave in ways that facilitate effective social interaction, possibly through reduced metabolic activity in prefrontal regions of the brain important for personality, affect, and inhibitory behavior.     

Sleep deprivation impairs object recognition in mice

Many studies in animals and humans suggest that sleep facilitates learning, memory consolidation, and retrieval. Moreover, sleep deprivation (SD) incurred after learning, impaired memory in humans, mice, rats, and hamsters. We investigated the importance of sleep and its timing in an object recognition task in OF1 mice subjected to 6h SD either immediately after the acquisition phase (0-6 SD) or 6h later (7-12 SD), and in corresponding undisturbed controls. Motor activity was continuously recorded with infrared sensors. All groups explored two familiar, previously encountered objects to a similar extent, both at the end of the acquisition phase and 24h later during the test phase, indicating intact familiarity detection. During the test phase 0-6 SD mice failed to discriminate between the single novel and the two familiar objects. In contrast, the 7-12 SD group and the two control groups explored the novel object significantly longer than the two familiar objects. Plasma corticosterone levels determined after SD did not differ from time-matched undisturbed controls, but were significantly below the level measured after learning alone. ACTH did not differ between the groups. Therefore, it is unlikely that stress contributed to the memory impairment. We conclude that the loss of sleep and the activities the mice engaged in during the SD, impaired recognition memory retrieval, when they occurred immediately after acquisition. The delayed SD enabled memory consolidation during the 6h when the mice were allowed to sleep, and had no detrimental effect on memory. Neither SD schedule impaired object familiarity processing, suggesting that only specific cognitive abilities were sensitive to the intervention. Sleep may either actively promote memory formation, or alternatively, sleep may provide optimal conditions of non-interference for consolidation.     

Individual differences in cortisol responses to fear and frustration during middle childhood

The purpose of this study was to examine individual differences in the activation and regulation of the hypothalamic-pituitary-adrenal (HPA) axis in prepubertal children after exposure to two different stress modalities and to evaluate the utility of an individual differences approach to the examination of HPA axis functioning. After a 30-min controlled baseline period, 73 7-year-olds (40 boys and 33 girls) were randomly assigned to a validity check condition or one of two experimental tasks designed to elicit fear or frustration. This was followed by a 60-min controlled regulation phase. A total of 17 saliva samples were collected, including 12 poststress samples at 5-min intervals. There was a significant stress modality effect, with children exposed to the fear condition reaching peak cortisol levels at 25 min poststress and those exposed to the frustration condition reaching peak levels at 45 min poststress. There was no difference in peak cortisol levels between the stress modalities. Individual variability across conditions was significant, with participants reaching peak levels as early as 10 min poststress and as late as 60 min poststress. Our data suggest that analysis of individual curves prior to making group-level comparisons may improve the explanatory power of HPA axis behavior models.     

One night of sleep deprivation affects reaction time, but not interference or facilitation in a Stroop task

The Stroop color-naming task is one of the most widely studied tasks involving the inhibition of a prepotent response, regarded as an executive function. Several studies have examined performance on versions of the Stroop task under conditions of acute sleep deprivation. Though these studies revealed effects on Stroop performance, the results often do not differentiate between general effects of sleep deprivation on performance and effects specifically on interference in the Stroop task. To examine the effect of prolonged wakefulness on performance on the Stroop task, we studied participants in a 40-h "constant routine" protocol during which they remained awake in constant conditions and performed a Stroop color-naming task every two hours. We found that reaction time was slowest when the color and word did not match (incongruent), fastest when the color and word did match (congruent), and intermediate when participants named the color of the non-word stimulus (neutral). Performance on all three trial types degraded significantly as a function of time awake. Extended wakefulness did not significantly change the additional time needed to respond when the color and word did not match (Stroop interference), nor did it change the amount of facilitation when color and word matched. These results indicate that one night of sleep deprivation influences performance on the Stroop task by an overall increase in response time, but does not appear to impact the underlying processes of interference or facilitation. The results suggest that the degree to which an "executive function" is affected by sleep deprivation may depend on the particular executive function studied and the degree to which it is subserved by the prefrontal cortex.     

Sleep deprivation and sustained attention performance: integrating mathematical and cognitive modeling

A long history of research has revealed many neurophysiological changes and concomitant behavioral impacts of sleep deprivation, sleep restriction, and circadian rhythms. Little research, however, has been conducted in the area of computational cognitive modeling to understand the information processing mechanisms through which neurobehavioral factors operate to produce degradations in human performance. Our approach to understanding this relationship is to link predictions of overall cognitive functioning, or alertness, from existing biomathematical models to information processing parameters in a cognitive architecture, leveraging the strengths from each to develop a more comprehensive explanation. The integration of these methodologies is used to account for changes in human performance on a sustained attention task across 88 h of total sleep deprivation. The integrated model captures changes due to time awake and circadian rhythms, and it also provides an account for underlying changes in the cognitive processes that give rise to those effects. The results show the potential for developing mechanistic accounts of how fatigue impacts cognition, and they illustrate the increased explanatory power that is possible by combining theoretical insights from multiple methodologies.     

When to cooperate and when to compete: Emotional intelligence in interpersonal decision-making

This study examined the relationship between emotional intelligence (EI), assessed with an ability test, and interpersonal decision-making using the Prisoner’s Dilemma Game (PDG). Previous research found that individuals who self-report high EI tend to cooperate more than others in the Prisoner’s Dilemma. We relativize these findings by showing that individuals scoring high on an ability measure of EI choose effective strategies to deal with three different PDG conditions during real interactions. This suggests that emotionally intelligent individuals are not rigidly predisposed to cooperate regardless of others’ behavior. Instead, EI is associated with the capacity to respond flexibly to others’ strategies and to the interaction context in order to maximize long-term gains – even when this means competing rather than cooperating.     

Sleep deprivation in Air National Guard medical personnel responding to simulated disaster-training exercises

National Guard personnel remain largely unstudied within the sleep research community, despite their unique and important role. In response, the purpose of this study was to investigate the extent of sleep deprivation in National Guard medical personnel from two separate Air Force Bases (AFBs) responding to simulated disaster-training exercises. National Guard medical personnel (N = 77) were fitted with wrist activity monitors (actigraphy) to objectively measure their sleep for 4 days of their civilian time (baseline), followed by a 4-day transition period from civilian to military duty, and a 3–5-day disaster-training exercise. Differences in sleep quantity, quality, and “cognitive effectiveness” were analyzed using generalized linear mixed models. Participants’ sleep quantity was significantly reduced from civilian to disaster-training periods, and their cognitive effectiveness also dropped significantly. National Guard medical personnel were sleep-deprived during a simulated disaster-training exercise, which, although a valid proxy for real-world disasters, is likely to be a conservative approximation of the stress and fatigue National Guard personnel experience during crisis response. As such, the need for targeted fatigue-related interventions to safeguard our service members during these critical times is clear.