Cognitive flexibility: A distinct element of performance impairment due to sleep deprivation

Modulation of Neural Compensatory Response by Duration of Sleep Deprivation in a Cognitive Flexibility Task

The neural compensation mechanism involves maintaining cognitive performance during sleep deprivation (SD) by triggering alternative neural activations. While cognitive task complexity modulates post-SD neural activation, the role of SD duration remains uncertain. Thirty-three healthy college students (16 male and 17 female) completed a 36-h SD protocol, performing a switching task at baseline (pre-SD), after 24 h of SD (SD-24), and after 36 h of SD (SD-36). Resting-state EEG signals were recorded for 5 min at each SD stage and analysed using Standardised Low-Resolution Electromagnetic Tomography. Behavioural results showed that task performance declined after SD-24 compared to pre-SD, but recovered toward baseline levels after SD-36. Additionally, cognitive flexibility was lower after SD-24 and SD-36 than pre-SD, with no significant difference observed between SD-24 and SD-36. EEG results indicated decreased activation of the orbitofrontal and superior frontal gyrus after SD-24 and SD-36 compared to pre-SD, but increased activation of the superior parietal lobe after SD-36 compared to SD-24. The results of this study suggest that compensatory mechanisms depend on SD duration, indicating that effective neural compensation requires sustained wakefulness to activate fully.

The Role of Sleep Quality and Sleepiness in the Relationship Between Cognitive Flexibility and Fatigue

This study aimed to determine the pathways linking cognitive flexibility to fatigue through the serial mediation effect of sleep quality and sleepiness in 564 healthy adults using various scales, including the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Chalder Fatigue Scale, and Cognitive Flexibility Inventory. Analysis was performed using two mediating variables (sleep quality and sleepiness) with age and gender as covariates. The simple mediation effect was evaluated using the Causal Step. The indirect effect was examined using bootstrap method and Sobel test. The total and direct effects of cognitive flexibility on fatigue were both found to be statistically significant. The research model revealed three significant indirect effects: cognitive flexibility affecting fatigue through sleep quality, cognitive flexibility affecting fatigue through sleepiness and cognitive flexibility affecting fatigue through both sleep quality and sleepiness. Additionally, serial mediation analysis showed that the relationship between cognitive flexibility and fatigue is sequentially mediated by sleep quality and sleepiness (B = -0.064, SE = 0.013, 95% CI: -0.070 to -0.017). All effects were confirmed through the 95% confidence intervals, which did not include zero, and with significant p values. These findings highlight the role of sleep quality and sleepiness as serial mediators of the relationship between cognitive flexibility and fatigue. The study's major contribution is to provide insight on the independent and serial mediating role of sleep quality and sleepiness in the relationship between cognitive flexibility to fatigue.

Effects of sleep deprivation on sports performance and perceived exertion in athletes and non-athletes: a systematic review and meta-analysis

Background

Sleep deprivation can significantly affect sports performance and the perception of fatigue. However, the impact of sleep deprivation on sports performance remains a subject of ongoing debate across different populations.

Objectives

This study aimed to investigate the effects of sleep deprivation on sports performance and ratings of perceived exertion (RPE) in different groups, as well as how different types of sleep deprivation affect these aspects.

Methods

This systematic review followed the PRISMA guidelines (PROSPERO CRD42023492792). Randomized controlled trials (RCTs) and randomized crossover studies published in any language or up to any date were eligible based on the P.I.C.O.S. criteria. The systematic search included databases such as PubMed, Cochrane, Embase, Web of Science, and EBSCO, covering studies up to September 2024. The Cochrane RoB 2 tool was used to assess the risk of bias. Meta-analysis was conducted using either a fixed-effect model or a random-effects model. This study conducted subgroup analyses based on different populations, types of sleep deprivation, and testing times.

Results

This review includes 45 studies, comprising 16 on aerobic endurance (AE) performance, 8 on anaerobic endurance (AnE) performance, 23 on explosive power (EP), 10 on maximum force (MF), 4 on speed, 4 on skill control, and 12 on rating of perceived exertion (RPE). The results indicate that sleep deprivation significantly impaired AE in athletes [SMD = -0.66; 95% CI (-1.28, -0.04); P = 0.04], as well as EP [SMD = -0.63; 95% CI (-0.94, -0.33); P < 0.00001], MF [SMD = -0.35; 95% CI (-0.56, -0.14); P = 0.001], speed [SMD = -0.52, 95% CI (-0.83, -0.22); P = 0.0008], skill control [SMD = -0.87; 95% CI (-1.7, -0.04); P = 0.04], and RPE [SMD = 0.39; 95% CI (0.11, 0.66); P = 0.006]. Additionally, AE was also reduced in healthy non-athletes [SMD = -1.02; 95% CI (-1.84, -0.21); P = 0.01]. During the sleep deprivation process, early sleep deprivation (PSDE) significantly reduced EP [SMD = -1.04; 95% CI (-1.58, -0.5); P = 0.0002], MF [SMD = -0.57; 95% CI (-0.94, -0.19); P = 0.003], speed [SMD = -0.78; 95% CI (-1.35, -0.2); P = 0.008], and RPE [SMD = 0.6; 95% CI (0.17, 1.02); P = 0.006]. Late sleep deprivation (PSDB) impacted speed [SMD = -0.57; 95% CI (-1.15, 0.01); P = 0.05], skill control [SMD = -2.12; 95% CI (-3.01, -1.24); P < 0.00001], and RPE [SMD = 0.47; 95% CI (0.02, 0.92); P = 0.04]. Overall, total sleep deprivation primarily affected AE [SMD = -0.56; 95% CI (-1.08, -0.05); P = 0.03]. In terms of testing phases, p.m. tests had a significant impact on AE [SMD = -1.4; 95% CI (-2.47, -0.34); P = 0.01], EP [SMD = -0.68; 95% CI (-1.06, -0.31); P = 0.0004], MF [SMD = -0.3; 95% CI (-0.51, -0.09); P = 0.005], skill control [SMD = -2.12; 95% CI (-3.01, -1.24); P < 0.00001], and RPE [SMD = 0.72; 95% CI (0.20, 1.24); P = 0.007]. In contrast, a.m. tests primarily affected speed [SMD = -0.81; 95% CI (-1.52, -0.1); P = 0.03] and RPE [SMD = 0.44; 95% CI (0.01, 0.86); P = 0.04].

Conclusion

Sleep deprivation significantly impairs athletes' performance across various domains, including AE, MF, speed, and skill control, while also exacerbating RPE. In contrast, although sleep deprivation also negatively affects the AE of healthy non-athletes. Furthermore, PSDE appears to have a more pronounced effect on sports performance overall. Additionally, performance assessments conducted in the p.m. have been shown to further impact sports performance. These findings are crucial for understanding how sleep deprivation impacts both athletes and non-athletes, particularly in the context of training and competitive settings.

Can sleep affect destination memory? A prospective narrative review

The destination memory is the ability of individuals to remember to whom the information has been delivered. The memory system is an essential and critical piece of social communication and human social cognition. Previously, research has been done on the relationship between source memory and sleep which are critical and fundamental processes influencing our daily lives. However, this present prospective narrative review sheds light on the idea of beginning new research to understand the relationship between destination memory and sleep. Although no such literature exists that can explain this relationship, this review will try to understand prospective future directions by synthesizing available literature on sleep and the source memory. The present narrative review provides an overview of research executed in the fields of source memory, destination memory, and sleep. Destination memory and source memory are the opposite sides of the same coin. They are a part of the episodic memory system. Research suggests that they share similarities, namely their contextual nature, involvement of the pre-frontal cortex (PFC), and role of the medial temporal lobe (MTL). Studies on the effect of sleep on source memory have indicated that it plays a role in consolidation. This consolidation involves binding the item to its context. Due to the shared characteristics of source and destination memory, it can be suggested that sleep may play a role in influencing destination memory. Understanding this relationship will have implications for enhancing social memory/communication efficacy through sleep hygiene.

The human factor and ergonomics in Patient Safety

The human condition is linked to error in any activity that is performed, and the healthcare world is no exception. The origin of human error does not lie within the perversity of human nature, instead, it has its origins in latent failures in the healthcare environment and is a consequence of the processes and procedures applied. The science of the Human Factor deals with the application of knowledge to people (capabilities, characteristics and limitations), with the design and the management of the equipment they use and with the environments in which they work and the activities they carry out. Part of the Human Factor are the non-technical skills. These skills greatly influence people's behavior and, therefore, their performance and the quality of healthcare in a very complex socio-technical system.

The Effect of Total Sleep Deprivation on the Cognitive and In-Game Performance of Rocket League Esport Players

Purpose

It is presumed by many that acute sleep loss results in degraded in-game esports (competitive, organized video game play) performance. However, this has not been experimentally investigated to date. The objective of the current experiment was to elucidate whether ~29hrs of total sleep deprivation impacts in-game performance for the popular esport Rocket League.

Patients and Methods

Twenty skill-matched pairs (N = 40 total) were recruited. Within each pair, one participant was assigned to an intervention group (TSD), while the other was assigned to a control group (CON). Two test sessions occurred; one while both participants were rested (baseline), and the other while the CON participant was rested but the TSD participant was sleep deprived (experimental).

Results

Following total sleep deprivation, TSD participants reported higher Karolinska Sleepiness Scale-measured subjective sleepiness and lower subjective alertness and motivation, as well as worsened PVT response speed and ~5 times greater PVT lapse incidence, and worsened response speed on a two-choice categorization task. However, overall in-game Rocket League performance did not worsen due to total sleep deprivation. Exploratory analyses of performance indicators suggest a potential shift toward a simpler and safer strategy following sleep deprivation.

Conclusion

Following a bout of ~29hrs total sleep deprivation, overall in-game Rocket League performance remained unaffected. This presents as a promising finding given the high potential for acute pre-competition sleep disturbance in esports, though habitual sleep remains a concern for esport athletes.

Phloretin alleviates sleep deprivation-induced cognitive impairment by reducing inflammation through PPARγ/NF-κB signaling pathway

Sleep loss leads to significant pathophysiological consequences, including cognitive impairment. The neuroinflammation are pivotal factors in the pathogenesis of cognitive impairment induced by sleep loss. The phloretin (PHL), derived from peel of juicy fruits, has demonstrated potent anti-inflammatory properties. However, the precise influence of PHL on the cognitive impairment triggered by sleep loss and its underlying mechanism remain uncertain. In the present study, mice were subjected to sleep deprivation (SD) paradigm. Cognitive impairment induced by SD were significantly relieved by administration of PHL in a dose-dependent manner. Furthermore, PHL not only mitigated the synaptic losses but also enhanced dendritic spine density and neuronal activity within mice hippocampus following exposure to SD. Moreover, PHL treatment decreased the microglial numbers and altered microglial morphology in the hippocampus to restore the M1/M2 balances; these effects were accompanied by regulation of pro-/anti-inflammatory cytokine production and secretion in SD-exposed mice. Additionally, in vivo and in vitro studies showed PHL might attenuate the inflammation through the PPARγ/NF-κB pathway. Our findings suggest that PHL exerts inhibitory effects on microglia-mediated neuroinflammation, thereby providing protection against cognitive impairment induced by SD through a PPAR-γ dependent mechanism. The results indicate PHL is expected to provide a valuable candidate for new drug development for SD-induced cognitive impairment in the future.

Sleep deprivation alters utilization of negative feedback in risky decision-making

Background

Sleep loss has sometimes catastrophic effects on risky decision-making. However, it is unknown to what extent such deficits are exacerbated with increasing duration of sleep deprivation (SD) and whether sustained vigilant attention mediates this sleep deprivation-induced deficit.

Methods

The present study aimed to investigate the effect of 36 hours of SD on 37 male college students' arousal, emotion, vigilant attention, and risky decision-making, using the Psychomotor Vigilance Test, the Game of Dice Task, and scales assessing fatigue, sleep, and emotions.

Results

Compared to baseline, SD significantly increased sleepiness, fatigue, and negative emotions, decreased positive emotions and vigilant attention, and led to a shift toward risky decision-making, and these effects often appeared 15 or 20 hours after SD. Interestingly, participants' ability to employ positive feedback was maintained, whereas their performance to utilize negative feedback was impaired even after 8 hours of sleep deprivation. Meanwhile, vigilant attention acted as a mediator between SD and risky decision-making (z = -1.97, 95% [-6.00, -0.30]).

Discussion

These results suggest that sleep-deprived individuals are unable to use negative feedback to optimize their judgments, which may account for their poor decision-making under risk.

The Selective Impairments of Total Sleep Deprivation on Alerting, Orienting, and Executive Control: Evidence from Event-Related Potentials

BACKGROUND

Many studies have shown that total sleep deprivation (TSD) impairs the attention network, which includes three subcomponents as follows: alerting, orienting, and executive control. However, the specific attention network(s) damaged by TSD remains unclear.

METHODS

Twenty two participants were enrolled to complete the attention network test (ANT) before and after 36 h of TSD with simultaneous electroencephalography recordings.

RESULTS

The repeated-measures analysis of variance of the response time (RT) suggested that the interaction effect between sleep conditions (before versus after TSD) and target congruence (incongruent versus congruent target) was significant; that is, the RT of the incongruent target was longer than that of the congruent target, whereas this difference disappeared after TSD. Furthermore, the interaction effect of sustained potential (SP) amplitude between the sleep conditions and target congruence was significant; that is, the incongruent target invoked a less positive sustained potential amplitude after than before TSD; whereas that invoked by the congruent target was not.

CONCLUSION

TSD selectively impairs attention networks. TSD affects the executive control network the most, which is followed by the alerting network rather than the orienting network. This provides a new perspective for understanding how shortened sleep affects attention.

CLINICAL TRIAL REGISTRATION

No: ChiCTR2400088448. Registered 19 August 2024, https://www.chictr.org.cn.

The association between insomnia symptoms and cognitive flexibility among undergraduates: An event-related potential study

OBJECTIVE

To explore the association between insomnia symptoms and cognitive flexibility among undergraduates, along with its potential neural mechanisms.

METHOD

A total of 102 participants were divided into insomnia (n = 55) and control (n = 47) groups based on sleep status. Cognitive flexibility was assessed using the Cognitive Flexibility Inventory (CFI) and the Number-Letter Task (N-L task). EEG data were recorded during the N-L task.

RESULTS

The insomnia group exhibited lower CFI scores and higher switch costs in reaction time and accuracy compared to the control group. ERP analysis showed differences in P2, N2, and P3 component amplitudes between the two groups, with reduced N2 amplitude in the insomnia group under repeat trials. Time-frequency analysis revealed larger theta band event related synchronization in the frontal region and smaller theta band ERS in the parietal region under switch trials in the control group; the alpha band event-related desynchronization in the parietal region under repeat trials was significantly smaller in the control group compared to switch trials.

CONCLUSION

Compared to undergraduates with normal sleep, those with insomnia symptoms exhibited reduced cognitive flexibility, which may be associated with some alterations in brain electrophysiological activities.

Consensus-Driven Recommendations to Support Physician Pregnancy, Adoption, Surrogacy, Parental Leave, and Lactation in Emergency Medicine

The emergency department clinical environment is unique, and guidelines for promoting supportive and equitable workplace cultures ensure success and longevity for pregnant persons and parents in emergency medicine. There is paucity, variability, and dissatisfaction with current parental (historically referred to as maternity and paternity) leave policies. This paper describes the development of consensus-derived recommendations to serve as a framework for emergency departments across the country for incorporating family-friendly policies. Policies that foster a family-inclusive workplace by allowing for professional advancement without sacrificing personal values regardless of sex, gender, and gender identity are critical for emergency medicine recruitment and retention.

Total Sleep Deprivation Triggers a Compensatory Mechanism During Conflict Monitoring Process: Evidence From Event-Related Potentials

Sleep deprivation impairs cognitive function and is accompanied by a simultaneous compensatory effect, one of the brain's capacities to maintain function in emergency situations. However, the time course of the compensatory effect is unclear. In this study, 22 male participants completed a pronunciation working memory task that included congruent and incongruent stimuli trials with EEG recordings before and after total sleep deprivation (TSD). Behavioral performance analysis showed that after TSD, the participants' reaction time (RT) was shortened, but accuracy was reduced significantly. Analysis of event-related potential (ERP) results showed that the amplitude of N2 (an early visual ERP) was larger (i.e., more negative) after TSD than at baseline. A significant interaction between congruency and sleep condition was seen. Compared to that before TSD, the increase in amplitude of P3 (a stimulus-induced positive deflection component) under an incongruent stimulus was larger than that under a congruent stimulus after TSD. Moreover, a significant negative correlation was found between P3 amplitude and RT. Our results suggest that TSD impairs cognitive function. Meanwhile, the brain activates a compensatory mechanism after TSD, which is comprehensive during the conflict-detection and information-updating stages. This study provides a fresh viewpoint for understanding how TSD affects cognitive function.

Sleep reactivity is associated with social anxiety and disordered-eating behaviors in college students

Objective: Investigate whether sleep reactivity was associated with social anxiety and disordered-eating behaviors in a college population. Participants: One hundred ninety-eight college-age men and women. Methods: Participants completed self-report measures of social anxiety, disordered-eating behaviors and sleep reactivity. Results: Sleep reactivity was associated with greater dietary restriction and purging, controlling for social anxiety but it was not associated with binge eating. Sleep reactivity was associated with elevated symptoms of social anxiety, controlling for disordered-eating behaviors. Conclusions: The results suggest that sleep reactivity represents a shared correlate of disordered-eating behaviors and social anxiety that may partially explain their co-occurrence. Interventions to help college students high in sleep reactivity effectively manage stress and regulate their sleep may aid in the prevention and treatment of social anxiety and disordered-eating behaviors.

The effect of 24-hour sleep deprivation on subjective time perception

In this study, we investigated the effect of 24-h total sleep deprivation on subjective time perception. Twenty-five participants aged 18-35 years (13 female and 12 male) were recruited. Time perception and cognitive assessments were performed twice: after a regular night's sleep and following a 24-h sleep deprivation. The retrospective and prospective tasks were used to measure time perception. In order to prevent order effect, the test orders were randomized. The Stroop test and the Wechsler Memory Scale-III were used to evaluate attention, processing speed, and memory. The repeated measures ANOVA was used to examine gender-by-sleep deprivation interactions on time perception. We found that retrospective time perception was significantly prolonged after sleep deprivation (p < 0.05). Women had a shorter prospective time estimation rate after adequate sleep than men, but this difference disappeared after sleep deprivation. The Stroop test showed improvement in cognitive flexibility after sleep deprivation (p < 0.05), and short-term or working memory appeared unaffected by one night of sleep deprivation. There was a negative correlation between sleepiness rate and working memory function in female subgroup. The results suggest that even short-term sleep deprivation can significantly affect time perception, which may have important implications in critical situations.

The Influence of Emotional Regulation and Cognitive Flexibility on Sleep Habits in Spanish Children and Adolescents through the Lens of Parents

BACKGROUND

Previous research studies have suggested the importance of studying the relationship between emotional regulation and sleep habits. Some investigations have especially focused on how emotional regulation could impact sleep habits in children and adolescents. Therefore, these researchers have stated there exists a two-way direction in this relationship.

OBJECTIVE

This study aimed to analyze the influence of emotional regulation on sleep habits in Spanish children and adolescents and the mediating role of anxiety in this relationship.

METHOD

Participants were 953 Spanish parents who completed the assessment protocol according to their children and adolescents' information.

RESULTS

The results revealed moderate-strong correlations between emotional regulation problems and sleep habit disturbances (r = 0.375, p < 0.001), trait (r = 0.488, p < 0.001) anxiety, and state (r = 0.589, p < 0.001) anxiety. Additionally, emotional regulation showed a direct impact on sleep habits (β = 0.011, p = 0.005). Trait and state anxiety demonstrated a significant mediating role in the relationship between emotional regulation and sleep habits.

CONCLUSIONS

Emotional regulation may have an impact on sleep habits during childhood and adolescence, suggesting the importance of early intervention focused on the emotions management and the prevention of sleep habit disturbances.

Effects of sleep disturbance on trauma-focused psychotherapy outcomes in posttraumatic stress disorder: A systematic review

This study aimed to synthesize existing research on the effects of sleep disturbances on trauma-focused psychotherapy outcomes in adults with posttraumatic stress disorder (PTSD). A systematic review using PubMed, PsycINFO, Embase, Web of Science, and PTSDpubs was performed up to April 2021. Two independent reviewers screened articles for inclusion, performed data extraction, and assessed risk of bias and certainty of the evidence. Narrative synthesis was conducted based on the type of sleep disorder symptom assessed. Sixteen primary studies were included in this review, the majority of which had a high overall risk of bias. Results suggested that sleep disorder symptoms were associated with higher overall PTSD severity across treatment; however, they did not interfere with treatment effectiveness, with the exception of sleep-disordered breathing. Improvements in insomnia, sleep duration, and sleep quality during treatment were associated with greater treatment gains. Certainty of the evidence ranged from low to very low. These results suggest that it may not be necessary to address sleep disorder symptoms prior to initiating trauma-focused psychotherapy. Instead, concurrent treatment of sleep- and trauma-related symptoms may be most beneficial. Continued research is needed to clarify the mechanistic relationship between sleep and treatment outcomes and to guide clinical decision-making.

MiR-181c-5p ameliorates learning and memory in sleep-deprived mice via HMGB1/TLR4/NF-κB pathway

Sleep deprivation (SD) can lead to cognitive impairment caused by neuroinflammation. MiR-181c-5p/HMGB1 axis plays a part in anti-inflammation effects. However, the mechanism that miR-181c-5p facilitates learning and memory in SD mice remains unclear. So we investigated the role of miR-181c-5p in learning and memory impairment induced by SD. We overexpressed miR-181c-5p in the mice hippocampus by injecting lentivirus vector-miR-181c-5p (LV-miR-181c-5p) particles. Mice were divided into four groups: control (Ctrl), SD, SD + miR-181c-5p and SD + vector. We found that mice in the third group showed ameliorated learning and memory compared with the fourth group. The content of ionized calcium binding adaptor molecule 1 (IBA-1) in the third group was decreased compared with the fourth group. Moreover, the expression levels of HMGB1, TLR4 and p-NF-κB in the hippocampus of overexpressed miR-181c-5p mice were reduced. In total, miR-181c-5p ameliorated learning and memory in SD mice via the HMGB1/TLR4/NF-κB pathway.

Effects of Sleep Deprivation on Performance during a Change Signal Task with Adaptive Dynamics

Augmented cognition, which refers to real-time modifications to a human-system interface to improve performance and includes dynamic task environments with automated adaptations, can serve to protect against performance impairment under challenging work conditions. However, the effectiveness of augmented cognition as a countermeasure for performance impairment due to sleep loss is unknown. Here, in a controlled laboratory study, an adaptive version of a Change Signal task was administered repeatedly to healthy adults randomized to 62 h of total sleep deprivation (TSD) or a rested control condition. In the computerized task, a left- or right-facing arrow was presented to start each trial. In a subset of trials, a second arrow facing the opposite direction was presented after a delay. Subjects were to respond within 1000 ms of the trial start by pressing the arrow key corresponding to the single arrow (Go trials) or to the second arrow when present (Change trials). The Change Signal Delay (CSD)-i.e., the delay between the appearance of the first and second arrows-was shortened following incorrect responses and lengthened following correct responses so that subsequent Change trials became easier or harder, respectively. The task featured two distinct CSD dynamics, which produced relatively stable low and high error rates when subjects were rested (Low and High Error Likelihood trials, respectively). During TSD, the High Error Likelihood trials produced the same, relatively high error rate, but the Low Error Likelihood trials produced a higher error rate than in the rested condition. Thus, sleep loss altered the effectiveness of the adaptive dynamics in the Change Signal task. A principal component analysis revealed that while subjects varied in their performance of the task along a single dominant dimension when rested, a second inter-individual differences dimension emerged during TSD. These findings suggest a need for further investigation of the interaction between augmented cognition approaches and sleep deprivation in order to determine whether and how augmented cognition can be relied upon as a countermeasure to performance impairment in operational settings with sleep loss.

Longitudinal Associations Among Symptoms of Family Intensive Care Unit Syndrome

BACKGROUND

Family intensive care unit (ICU) syndrome, a comorbid response to another person's stay in the ICU, is characterized by emotional distress, poor sleep health, and decision fatigue.

OBJECTIVES

This pilot study examined associations among symptoms of emotional distress (anxiety and depression), poor sleep health (sleep disturbance), and decision fatigue in a sample of family members of patients in the ICU.

METHODS

The study used a repeated-measures, correlational design. Participants were 32 surrogate decision makers of cognitively impaired adults who had at least 72 consecutive hours of mechanical ventilation within the neurological, cardiothoracic, and medical ICUs at an academic medical center in northeast Ohio. Surrogate decision makers with a diagnosis of hypersomnia, insomnia, central sleep apnea, obstructive sleep apnea, or narcolepsy were excluded. Severity of symptoms of family ICU syndrome was measured at 3 time points in 1 week. Zero-order Spearman correlations of the study variables were interpreted at baseline and partial Spearman correlations of study variables were interpreted 3 days and 7 days after baseline.

RESULTS

The study variables showed moderate to large associations at baseline. Baseline anxiety and depression were associated with each other and with decision fatigue at day 3. Baseline sleep disturbance was associated with anxiety, depression, and decision fatigue at day 7.

CONCLUSIONS

Understanding the temporal dynamics and mechanisms of the symptoms of family ICU syndrome can inform clinical, research, and policy initiatives that enhance the provision of family-centered critical care.

Postoperative delirium: identifying the patient at risk and altering the course: A narrative review

Postoperative delirium (POD) is a common neurocognitive syndrome seen in older patients after major surgery. POD is linked to longer stays in hospital and intensive care, a greater incidence of postoperative complications, worse functional outcome, and higher mortality. Researchers have not yet fully elucidated the exact pathophysiology of POD. Several risk factors that contribute to the development of POD have been identified, such as advanced age, cardiac or hip surgery, preoperative cognitive decline or delirium, disturbances in brain levels of neurotransmitters and information processing, oxidative stress and neuro-inflammation. Identifying patients at risk for POD enables a more precise and efficient allocation of medical resources and facilitates POD prevention and management. The present review addresses how to identify patients at risk of POD and summarizes the currently available evidence and best-practice recommendations for peri-operative management and prevention of POD.

Effects of total sleep deprivation on components of top-down attentional control using a flexible attentional control task

Sleep deprivation consistently decreases vigilant attention, which can lead to difficulty in performing a variety of cognitive tasks. However, sleep-deprived individuals may be able to compensate for degraded vigilant attention by means of top-down attentional control. We employed a novel task to measure the degree to which individuals overcome impairments in vigilant attention by using top-down attentional control, the Flexible Attentional Control Task (FACT). The FACT is a two-choice task that has trials with valid, invalid, and neutral cues, along with an unexpected switch in the probability of cue validity about halfway in the task. The task provides indices that isolate performance components reflecting vigilant attention and top-down attentional control. Twelve healthy young adults completed an in-laboratory study. After a baseline day, the subjects underwent 39 hours of total sleep deprivation (TSD), followed by a recovery day. The FACT was administered at 03:00, 11:00, and 19:00 during sleep deprivation (TSD condition) and at 11:00 and 19:00 after baseline sleep and at 11:00 after recovery sleep (rested condition). When rested, the subjects demonstrated both facilitation and interference effects on cued trials. While sleep deprived, the subjects showed vigilant attention deficits on neutral cue trials, and an impaired ability to reduce these deficits by using predictive contextual cues. Our results indicate that the FACT can dissociate vigilant attention from top-down attentional control. Furthermore, they show that during sleep deprivation, contextual cues help individuals to compensate partially for impairments in vigilant attention, but the effectiveness of top-down attentional control is diminished.

Temporary amnesia from sleep loss: A framework for understanding consequences of sleep deprivation

Throughout its modern history, sleep research has been concerned with both the benefits of sleep and the deleterious impact of sleep disruption for cognition, behavior, and performance. When more specifically examining the impact of sleep on memory and learning, however, research has overwhelmingly focused on how sleep following learning facilitates memory, with less attention paid to how lack of sleep prior to learning can disrupt subsequent memory. Although this imbalance in research emphasis is being more frequently addressed by current investigators, there is a need for a more organized approach to examining the effect of sleep deprivation before learning. The present review briefly describes the generally accepted approach to analyzing effects of sleep deprivation on subsequent memory and learning by means of its effects on encoding. Then, we suggest an alternative framework with which to understand sleep loss and memory in terms of temporary amnesia from sleep loss (TASL). The review covers the well-characterized properties of amnesia arising from medial temporal lobe lesions and shows how the pattern of preserved and impaired aspects of memory in amnesia may also be appearing during sleep loss. The view of the TASL framework is that amnesia and the amnesia-like deficits observed during sleep deprivation not only affect memory processes but will also be apparent in cognitive processes that rely on those memory processes, such as decision-making. Adoption of the TASL framework encourages movement away from traditional explanations based on narrowly defined domains of memory functioning, such as encoding, and taking instead a more expansive view of how brain structures that support memory, such as the hippocampus, interact with higher structures, such as the prefrontal cortex, to produce complex cognition and behavioral performance, and how this interaction may be compromised by sleep disruption.

Total sleep deprivation selectively impairs motor preparation sub-stages in visual search task: Evidence from lateralized readiness potentials

Introduction

Many studies have provided evidence of a damage effect triggered by total sleep deprivation (TSD). However, it remains unclear whether the motor preparation processing is affected by TSD.

Methods

In the current study, 23 volunteers performed a stimulus-response compatibility visual search task before and after TSD while undergoing spontaneous electroencephalography (EEG).

Results

Repeated-measures analysis of variance revealed that: Compared with that at baseline, the visual search task's accuracy decreased after TSD, while the response time variance increased significantly. The peak amplitude of the stimulus-locked lateralized readiness potential (LRP) induced by a compatible stimulus was significantly more negative than that induced by an incompatible stimulus before TSD, whereas this difference was not significant after TSD. However, when taking sleep status into consideration, there were no significant main or interaction effects on response-locked LRPs.

Discussion

Our findings suggest that TSD damages visual search behavior, selectively impairs the earlier sub-stages of motor preparation (sensory integration). These findings will provide a new perspective for understanding the effects of sleep loss.

Image discrimination reversal learning is impaired by sleep deprivation in rats: Cognitive rigidity or fatigue?

Introduction

Insufficient sleep is pervasive worldwide, and its toll on health and safety is recapitulated in many settings. It is thus important to understand how poor sleep affects the brain and decision making. A robust literature documents the adverse effects of sleep deprivation on cognitive processes including cognitive flexibility, which is the capacity to appraise new feedback and make behavioral adjustments to respond appropriately. Animal models are often used to unravel the molecules, genes and neural circuits that are altered by sleep loss. Herein we take a translational approach to model the effects of sleep deprivation on cognitive rigidity, i.e., impaired cognitive flexibility in rats.

Methods

There are several approaches to assess cognitive rigidity; in the present study, we employ a pairwise discrimination reversal task. To our knowledge this is the first time this paradigm has been used to investigate sleep deprivation. In this touchscreen operant platform, we trained rats to select one of two images to claim a sucrose pellet reward. If the non-rewarded image was selected the rats proceeded to a correction trial where both images were presented in the same position as before. This image presentation continued until the rat selected the correct image. Once rats reached performance criteria, the reward contingencies were reversed. In one group of rats the initial reversal session was preceded by 10 h of sleep deprivation. We compared those rats to controls with undisturbed sleep on the number of sessions to reach performance criteria, number of trials per session, response latencies, correct responses, errors, perseverative errors and perseveration bouts in the initial training and reversal phases.

Results

We report that on reversal session one, sleep deprived rats completed a fraction of the trials completed by controls. On subsequent reversal sessions, the sleep deprived rats struggled to adapt to the reversed contingencies despite completing a similar number of trials, suggesting an effect of cognitive rigidity separate from fatigue.

Discussion

We discuss the delayed performance dynamics incurred by sleep loss in the context of fatigue and the implications of using pairwise discrimination reversal as a model to further examine the effects of sleep loss on adaptive decision making.

Sleep loss suicidal ideation: the role of trait extraversion

Background: It is known that sleep disturbance is associated with increased suicidal thinking. Moreover, completed suicides, when adjusted for the proportion of the populace that is awake at a given time, are more probable during the late night/early morning hours. Despite these concerns, no studies have examined the role of trait-like individual differences in vulnerability to suicidal ideation during sleep deprivation or insomnia. In two separate studies, we examined whether the trait of extraversion is predictive of changes in suicidal thinking following two nights of sleep deprivation and among individuals meeting the criteria for insomnia.

Methods:Study 1: Twenty-five healthy military personnel (20 males), ages 20–35 completed the NEO-PI-R Extraversion scale and the Suicidal Ideation (SUI) scale of the Personality Assessment Inventory (PAI). Participants completed 77 h of continuous sleep deprivation. After 56 h of sleep deprivation, participants completed the SUI scale a second time. We predicted a change in SUI scores from baseline extraversion. Study 2: 2,061 adults aged 18–79 (900 males) were divided into two groups based on the clinical threshold (≥ 10) on the Insomnia Severity Index (ISI) and completed measures of extraversion and depression, including the suicide item of the Patient Health Questionnaire-9 (PHQ9).

Results:Study 1: After controlling for the caffeine group and changes in PAI Depression, Extraversion scores were used to predict changes in SUI scores using stepwise multiple linear regression. Higher Extraversion was significantly associated with increased non-clinical suicidal ideation following sleep loss, β = 0.463, partial r = 0.512, p = 0.013. Study 2: After controlling for depression, the effect of insomnia on suicidal ideation was moderated by trait extraversion (p < 0.0001). Overall, the presence or absence of insomnia had little effect on individuals low in trait extraversion (i.e., introverts), but insomnia was associated with significantly higher suicidal ideation among high trait extraverted individuals.

Conclusions: Higher trait extraversion was associated with increased vulnerability to suicidal ideation between rested baseline and total sleep deprivation and was associated with greater suicidal ideation among those meeting criteria for clinically severe insomnia. These findings point to a potential trait-like vulnerability factor that may further our understanding of sleep disruption in the phenomenology of suicide.

Does sleep duration moderate genetic and environmental contributions to cognitive performance?

While prior research has demonstrated a relationship between sleep and cognitive performance, how sleep relates to underlying genetic and environmental etiologies contributing to cognitive functioning, regardless of the level of cognitive function, is unclear. The present study assessed whether the importance of genetic and environmental contributions to cognition vary depending on an individual's aging-related sleep characteristics. The large sample consisted of twins from six studies within the Interplay of Genes and Environment across Multiple Studies (IGEMS) consortium spanning mid- to late-life (Average age [Mage] = 57.6, range = 27-91 years, N = 7052, Female = 43.70%, 1525 complete monozygotic [MZ] pairs, 2001 complete dizygotic [DZ] pairs). Quantitative genetic twin models considered sleep duration as a primary moderator of genetic and environmental contributions to cognitive performance in four cognitive abilities (Semantic Fluency, Spatial-Visual Reasoning, Processing Speed, and Episodic Memory), while accounting for age moderation. Results suggested genetic and both shared and nonshared environmental contributions for Semantic Fluency and genetic and shared environmental contributions for Episodic Memory vary by sleep duration, while no significant moderation was observed for Spatial-Visual Reasoning or Processing Speed. Results for Semantic Fluency and Episodic Memory illustrated patterns of higher genetic influences on cognitive function at shorter sleep durations (i.e. 4 hours) and higher shared environmental contributions to cognitive function at longer sleep durations (i.e. 10 hours). Overall, these findings may align with associations of upregulation of neuroinflammatory processes and ineffective beta-amyloid clearance in short sleep contexts and common reporting of mental fatigue in long sleep contexts, both associated with poorer cognitive functioning.

Impairment of executive functions due to sleep alterations: An integrative review on the use of P300

Objective

Cognitive impairment due to sleep deprivation (SD) is an important global health concern as part of the growing rates of sleep disorders and sleep deprivation worldwide. Amongst the affected cognitive processes, the effects of SD on the executive functions (EFs) show diverse methods and inconclusive or contradictory results, highlighting the importance of further research in this field. Considering this scenario, we evaluate one of the most used methods for objectively evaluating EFs on SD: the event-related potential (ERP) P300.

Methods

Our study provides a comprehensive review on the use of P300 for evaluating executive functions in sleep alterations on subjects of all ages, as well as an analysis on the efficiency of P300 as an assessment method for executive functions compared to traditional neurocognitive batteries. We review the benefits of P300 application for multiple sleep/wake alterations, whether evoked in laboratory or as part of pre-existing sleep disorders.

Results

We assess the diverse protocols used to elicit and complement P300, the most identified alterations in amplitude and latency, and suggest new lines of study that could benefit from P300 within the field.

Conclusion

We conclude that P300 is a valuable asset for evaluating executive dysfunction under sleep deprivation both as a standalone protocol and in conjunction with subjective methods, with consistently significant results in assessing executive dysfunction in a diversity of subjects and etiologies.

Electrodermal Activity Is Sensitive to Sleep Deprivation but Does Not Moderate the Effect of Total Sleep Deprivation on Affect

Emotion is characterized by dimensions of affective valence and arousal, either or both of which may be altered by sleep loss, thereby contributing to impaired regulatory functioning. Controlled laboratory studies of total sleep deprivation (TSD) generally show alterations in physiological arousal and affective state, but the relationship of affect and emotion with physiological arousal during TSD has not been well characterized. Established methods for examining physiological arousal include electrodermal activity (EDA) measures such as non-specific skin conductance responses (NSSCR) and skin conductance level (SCL). These measures are robust physiological markers of sympathetic arousal and have been linked to changes in experienced emotion. To explore the link between physiological arousal and affect during sleep deprivation, we investigated individuals' EDA under TSD and its relationship to self-reported affect. We also investigated the relationship of EDA to two other measures known to be particularly sensitive to the arousal-decreasing effects of TSD, i.e., self-reported sleepiness and performance on a vigilant attention task. Data were drawn from three previously published laboratory experiments where participants were randomly assigned to either well-rested control (WRC) or 38 h of TSD. In this data set, comprising one of the largest samples ever used in an investigation of TSD and EDA (N = 193 with 74 WRC and 119 TSD), we found the expected impairing effects of TSD on self-reported affect and sleepiness and on vigilant attention. Furthermore, we found that NSSCR, but not SCL, were sensitive to TSD, with significant systematic inter-individual differences. Across individuals, the change in frequency of NSSCR during TSD was not predictive of the effect of TSD on affect, sleepiness, or vigilant attention, nor was it related to these outcomes during the rested baseline. Our findings indicate that while physiological arousal, as measured by EDA, may be useful for assessing TSD-related changes in non-specific arousal at the group level, it is not associated with individuals' self-reported affect at rest nor their change in affect during TSD. This suggests that an essential aspect of the relationship between physiological arousal and self-reported affect is not well captured by EDA as measured by NSSCR.

Impact of spaceflight stressors on behavior and cognition: A molecular, neurochemical, and neurobiological perspective

The response of the human body to multiple spaceflight stressors is complex, but mounting evidence implicate risks to CNS functionality as significant, able to threaten metrics of mission success and longer-term behavioral and neurocognitive health. Prolonged exposure to microgravity, sleep disruption, social isolation, fluid shifts, and ionizing radiation have been shown to disrupt mechanisms of homeostasis and neurobiological well-being. The overarching goal of this review is to document the existing evidence of how the major spaceflight stressors, including radiation, microgravity, isolation/confinement, and sleep deprivation, alone or in combination alter molecular, neurochemical, neurobiological, and plasma metabolite/lipid signatures that may be linked to operationally-relevant behavioral and cognitive performance. While certain brain region-specific and/or systemic alterations titrated in part with neurobiological outcome, variations across model systems, study design, and the conspicuous absence of targeted studies implementing combinations of spaceflight stressors, confounded the identification of specific signatures having direct relevance to human activities in space. Summaries are provided for formulating new research directives and more predictive readouts of portending change in neurobiological function.

Perioperative neurocognitive disorders: A narrative review focusing on diagnosis, prevention, and treatment

Perioperative neurocognitive disorders (NCDs) refer to neurocognitive abnormalities detected during the perioperative periods, including preexisting cognitive impairment, preoperative delirium, delirium occurring up to 7 days after surgery, delayed neurocognitive recovery, and postoperative NCD. The Diagnostic and Statistical Manual of Mental Disorders‐5th edition (DSM‐5) is the golden standard for diagnosing perioperative NCDs. Given the impracticality of using the DSM‐5 by non‐psychiatric practitioners, many diagnostic tools have been developed and validated for different clinical scenarios. The etiology of perioperative NCDs is multifactorial and includes predisposing and precipitating factors. Identifying these risk factors is conducive to preoperative risk stratification and perioperative risk reduction. Prevention for perioperative NCDs should include avoiding possible contributors and implementing nonpharmacologic and pharmacological interventions. The former generally includes avoiding benzodiazepines, anticholinergics, prolonged liquid fasting, deep anesthesia, cerebral oxygen desaturation, and intraoperative hypothermia. Nonpharmacologic measures include preoperative cognitive prehabilitation, comprehensive geriatric assessment, implementing fast‐track surgery, combined use of regional block, and sleep promotion. Pharmacological measures including dexmedetomidine, nonsteroidal anti‐inflammatory drugs, and acetaminophen are found to have beneficial effects. Nonpharmacological treatments are the first‐line measures for established perioperative NCDs. Pharmacological treatments are still limited to severely agitated or distressed patients.

The contribution of sleep to anorexia nervosa severity

PURPOSE

Anorexia nervosa (AN) is associated with poor sleep and altered circadian rhythms. Evidence is unclear as to whether these features relate to ongoing psychiatric symptoms of AN, or are merely concomitant with low weight. In this study, we sought to evaluate subjective sleep quality and sleep-wake preferences in a sample of individuals with lifetime AN. Furthermore, we aimed to examine whether sleep quality would significantly predict AN symptom severity, after accounting for demographic features and negative emotions (depression, anxiety and stress).

METHODS

Adults with a lifetime diagnosis of AN (n = 96) or no lifetime psychiatric diagnoses (NC; n = 246) completed an online survey assessing demographics, sleep quality, circadian sleep-wake preferences, eating disorder symptoms, and negative emotions.

RESULTS

AN participants reported significantly poorer sleep quality overall, including increased sleep disturbances, use of sleep medications, and daytime dysfunction, as compared to NC participants. Groups did not differ significantly in circadian sleep-wake preferences. Regression analysis showed that among AN participants, sleep quality and negative emotions significantly predicted AN symptom severity, while sex and body mass index (BMI) did not.

CONCLUSION

The findings demonstrate that poor sleep quality was associated with more severe symptoms of AN, even when accounting for negative emotions and BMI. Future research should investigate causal interactions between sleep quality and AN symptom severity longitudinally and across different recovery stages.

LEVEL OF EVIDENCE

Level III-Cohort and case-control analytic studies.

Bright light exposure during simulated night work improves cognitive flexibility

Night work leads to sleepiness and reduced vigilant attention during work hours, and bright light interventions may reduce such effects. It is also known that total sleep deprivation impairs cognitive flexibility as measured by reversal learning tasks. Whether night work impairs reversal learning task performance or if bright light can mitigate reversal learning deficits during night work is unclear. In this counterbalanced crossover study (ClinicaTrials.gov Identifier NCT03203538), young healthy individuals completed a reversal learning task twice during each of three consecutive simulated night shifts (23:00-07:00 h). The night shifts were performed in a laboratory under a full-spectrum (4000 K) bright light (~900 lx) and a standard light (~90 lx) condition. Reversal learning task performance was reduced towards the end of the night shifts (04:50 h), compared to the first part of the night shifts (00:20 h) in both light conditions. However, with bright light, the reversal learning task performance improved towards the end of the night shifts, compared to standard light. The study shows that bright light may mitigate performance deficits on a reversal learning task during night work and implies that bright light interventions during night work may be beneficial not only for vigilant attention but also for cognitive flexibility.

Total Sleep Deprivation Triggers Greater Activation in the Parietal Brain in the Visual Working Memory Updating Processes: An Event-Related Potentials Study

Working memory functions are known to be altered after total sleep deprivation (TSD). However, few studies have explored the deficits of working memory updating (WMU) after TSD, or the underlying electrophysiological mechanisms of these alterations. In the current exploratory study, we enrolled 14 young male volunteers who performed two kinds of WMU tasks—spatial and object two-back tasks—with simultaneous electroencephalography recordings under two sleep conditions: a normal sleep baseline condition and after 36 h of TSD. Repeated-measures analysis of variance showed that compared with those at baseline, the rates of correct responses in the WMU tasks decreased significantly after TSD. Analysis of event-related potentials revealed that the average amplitude of P3 components decreased significantly in the frontal and central brain regions and increased significantly in the parietal brain regions. Our findings suggest that TSD damages WMU behavior, impairs cognitive functions in the frontal and central brain regions, and triggers greater activation in the parietal brain regions. This is the first study to report the existence of event-related compensatory neural activity. This event-related compensatory effect may provide a new perspective for understanding the mechanisms underlying the influences triggered by sleep loss.

Local sleep: A new concept in brain plasticity

Traditionally, sleep and wakefulness have been considered as two global, mutually exclusive states. However, this view has been challenged by the discovery that sleep and wakefulness are actually locally regulated and that islands of these two states may often coexist in the same individual. Importantly, such a local regulation seems to be the key for many essential functions of sleep, including the maintenance of cognitive efficiency and the consolidation of new skills and memories. Indeed, local changes in sleep-related oscillations occur in brain areas that are used and involved in learning during wakefulness. In turn, these changes directly modulate experience-dependent brain adaptations and the consolidation of newly acquired memories. In line with these observations, alterations in the regional balance between wake- and sleep-like activity have been shown to accompany many pathologic conditions, including psychiatric and neurologic disorders. In the last decade, experimental research has started to shed light on the mechanisms involved in the local regulation of sleep and wakefulness. The results of this research have opened new avenues of investigation regarding the function of sleep and have revealed novel potential targets for the treatment of several pathologic conditions.

Ascertaining Design and Implementation Requirements for a Perioperative Neurocognitive Training Intervention for the Prevention of Persistent Pain After Surgery

BACKGROUND

Persistent postsurgical pain (PPSP) is a common complication that impacts quality of life, often necessitating long-term opioid treatment. Certain neurocognitive factors, including reduced performance on cognitive flexibility tasks, are associated with increased risk of PPSP. We examine the perceptions of surgical patients and clinicians with regard to perioperative pain management activities and needs; patient acceptance and use of a perioperative neurocognitive training intervention; and implementation feasibility.

METHODS

We conducted both individual and focus group interviews with patients undergoing thoracic surgery and clinicians in an academic medical center. The Consolidated Framework for Intervention Research guided the development of interview questions related to the adoption and implementation of a neurocognitive intervention to mitigate PPSP. A thematic analysis was used to analyze the responses.

RESULTS

Forty patients and 15 clinicians participated. Interviews revealed that there is minimal discussion between clinicians and patients about PPSP. Most participants were receptive to a neurocognitive intervention to prevent PPSP, if evidence demonstrating its effectiveness were available. Potential barriers to neurocognitive training program adoption included fatigue, cognitive overload, lack of familiarity with the technology used for delivering the intervention, and immediate postoperative pain and stress. Implementation facilitators would include patient education about the intervention, incentives for its use, and daily reminders.

CONCLUSION

The study identified several guiding principles for addressing patients' and clinicians' barriers to effectively implementing a neurocognitive training intervention to mitigate PPSP after surgery. To ensure the sustainability of neurocognitive interventions for preventing PPSP, such interventions would need to be adapted to meet patients' and clinicians' needs within the perioperative context.

Hydrogen sulfide antagonizes sleep deprivation-induced depression- and anxiety-like behaviors by inhibiting neuroinflammation in a hippocampal Sirt1-dependent manner

Increasing evidence confirms that sleep deprivation (SD), which induces hippocampal neuroinflammation, is a risk factor for depression. Hydrogen sulfide (H₂S) is a novel neuromodulator that plays antidepressant-like role. Silent mating type information regulation 2 homolog 1 (Sirt1) is well-characterized as a regulator of mood disorder. Furthermore, we have previously reported that H₂S upregulates Sirt1 expression in the hippocampus of SD-exposed rats. Here, we explored whether H₂S ameliorates depression- and anxiety-like behaviors as well as hippocampal neuroinflammatory in SD-exposed rats and whether Sirt1 mediates these protective roles of H₂S. In the present work, we showed that NaHS (a donor of H₂S) significantly alleviated depression- and anxiety-like behaviors in the SD-exposed rats tested by novelty-suppressed feeding test (NST), forced swim test (FST), tail suspension test (TST), and elevated plus maze test (EPMT) and that NaHS attenuates neuroinflammatory in the hippocampus of SD-exposed rats, as evidenced by reducing the levels of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and chemokine CCL2, as well as increasing the levels of anti-inflammatory cytokines (IL-4 and IL-10) in the hippocampus. However, Sirt1 inhibitor reversed the protective effects of H₂S against SD-induced depression- and anxiety-like behaviors as well as hippocampal neuroinflammatory. In conclusion, H₂S antagonizes SD-induced depression- and anxiety-like behaviors and neuroinflammation, which is required hippocampal Sirt1. These findings suggested that H₂S is a novel approach to prevent SD-induced depression and anxiety.

Floor vibrations for motivation and feedback in the rat vibration actuating search task

Motivating rodents to perform cognitive tasks often relies on the application of aversive stimuli. The Vibration Actuating Search Task (VAST) is a novel open-field task in which gradient floor vibration provides motivation for the rodent to navigate in the direction of diminishing vibration to an unmarked target destination. Using floor vibration as a motivational stimulus may overcome several of the potential confounds associated with stimuli used in other tasks. In a series of three experiments, we determined whether (1) rats exhibit place preference for floor vibration over other aversive stimuli (i.e., water, foot shock, and bright light), (2) exposure to floor vibration is associated with a lower corticosterone response than exposure to these other stimuli, (3) rats successfully acquire the VAST, and (4) VAST performance is sensitive to 6 h of sleep deprivation (SD). Our results showed that rats exhibited place preference for vibration over water, foot shock, and bright light environments, and that corticosterone levels were lower in rats exposed to vibration than those exposed to water. VAST performance also significantly improved over two days of testing for some metrics, and SD impaired VAST performance. Overall, we conclude that (1) rats exhibit place preference for vibration over other stimuli commonly used to motivate task performance, (2) the vibrations employed by the VAST produce lower concentrations of circulating corticosterone than forced swimming, (3) rats can learn to use gradient floor vibration as a mode of performance feedback within two days of testing, and (4) VAST performance is substantially impaired by SD. Thus, the VAST is an effective and practical testbed for studying the mechanisms by which SD causes deficits in feedback-dependent decision making.

At the intersection of sleep deficiency and opioid use: mechanisms and therapeutic opportunities

Due to the ongoing opioid epidemic, innovative scientific perspectives and approaches are urgently needed to reduce the unprecedented personal and societal burdens of nonmedical and recreational opioid use. One promising opportunity is to focus on the relationship between sleep deficiency and opioid use. In this review, we examine empirical evidence: (1) at the interface of sleep deficiency and opioid use, including hypothesized bidirectional associations between sleep efficiency and opioid abstinence; (2) as to whether normalization of sleep deficiency might directly or indirectly improve opioid abstinence (and vice versa); and (3) regarding mechanisms that could link improvements in sleep to opioid abstinence. Based on available data, we identify candidate sleep-restorative therapeutic approaches that should be examined in rigorous clinical trials.

The effect of sleep restriction on cognitive performance in elite cognitive performers: a systematic review

STUDY OBJECTIVES

To synthesize original articles exploring the effects of sleep restriction on cognitive performance specifically for Elite Cognitive Performers, i.e. those who engage in cognitively demanding tasks with critical or safety-critical outcomes in their occupation or area of expertise.

METHODS

Backward snowballing techniques, gray literature searches, and traditional database searches (Embase, MEDLINE, Web of Science, Google Scholar, PSYCinfo, and SportDiscus) were used to obtain relevant articles. A quality assessment was performed, and the risk of training effects was considered. Results were narratively synthesized. Fourteen articles fit the criteria. Cognitive outcomes were divided into three categories defined by whether cognitive demands were "low-salience," "high-salience stable," or "high-salience flexible."

RESULTS

Low-salience tests (i.e. psychomotor vigilance tasks & serial reaction tests), mainly requiring vigilance and rudimentary attentional capacities, were sensitive to sleep restriction, however, this did not necessarily translate to significant performance deficits on low-salience occupation-specific task performance. High-salience cognitive outcomes were typically unaffected unless when cognitive flexibility was required.

CONCLUSIONS

Sleep restriction is of particular concern to occupations whereby individuals perform (1) simple, low-salience tasks or (2) high-salience tasks with demands on the flexible allocation of attention and working memory, with critical or safety-critical outcomes.

Sleep Deprivation Impairs Binding of Information with Its Context

Binding information to its context in long-term memory is critical for many tasks, including memory tasks and decision making. Failure to associate information to its context could be an important aspect of sleep deprivation effects on cognition, but little is known about binding problems from being sleep-deprived at the time of encoding. We studied how sleep deprivation affects binding using a well-established paradigm testing the ability to remember auditorily presented words (items) and their speakers (source context). In a laboratory study, 68 healthy young adults were randomly assigned to total sleep deprivation or a well-rested control condition. Participants completed an affective item and source memory task twice: once after 7h awake during baseline and again 24h later, after nearly 31h awake in the total sleep deprivation condition or 7h awake in the control condition. Participants listened to negative, positive, and neutral words presented by a male or female speaker and were immediately tested for recognition of the words and their respective speakers. Recognition of items declined during sleep deprivation, but even when items were recognized accurately, recognition of their associated sources also declined. Negative items were less bound with their sources than positive or neutral items,but sleep deprivation did not significantly affect this pattern.Our findings indicate that learning while sleep-deprived disrupts the binding of information to its context independent of item valence. Such binding failures may contribute to sleep deprivation effects on tasks requiring the ability to bind new information together in memory.

New insights into the cognitive effects of sleep deprivation by decomposition of a cognitive throughput task

STUDY OBJECTIVES

A cognitive throughput task known as the Digit Symbol Substitution Test (DSST) (or Symbol Digit Modalities Test) has been used as an assay of general cognitive slowing during sleep deprivation. Here, the effects of total sleep deprivation (TSD) on specific cognitive processes involved in DSST performance, including visual search, spatial memory, paired-associate learning, and motor response, were investigated through targeted task manipulations.

METHODS

A total of 12 DSST variants, designed to manipulate the use of specific cognitive processes, were implemented in two laboratory-based TSD studies with N = 59 and N = 26 subjects, respectively. In each study, the Psychomotor Vigilance Test (PVT) was administered alongside the DSST variants.

RESULTS

TSD reduced cognitive throughput on all DSST variants, with response time distributions exhibiting rightward skewing. All DSST variants showed practice effects, which were however minimized by inclusion of a pause between trials. Importantly, TSD-induced impairment on the DSST variants was not uniform, with a principal component analysis revealing three factors. Diffusion model decomposition of cognitive processes revealed that inter-individual differences during TSD on a two-alternative forced choice DSST variant were different from those on the PVT.

CONCLUSIONS

While reduced cognitive throughput has been interpreted to reflect general cognitive slowing, such TSD-induced impairment appears to reflect cognitive instability, like on the PVT, rather than general slowing. Further, comparisons between task variants revealed not one, but three distinct underlying processes impacted by sleep deprivation. Moreover, the practice effect on the task was found to be independent of the TSD effect and minimized by a task pacing manipulation.

Why Do Haul Truck Fatal Accidents Keep Occurring?

Powered haulage continues to be a large safety concern for the mining industry, accounting for approximately 50% of the mining fatal accidents every year. Among these fatal accidents, haul-truck-related accidents are the most common, with 6 of 28 and 6 of 27 fatal accidents occurring in 2017 and 2018, respectively. To better understand why these accidents continue to occur and what can be done to prevent them, researchers reviewed the 91 haul-truck-related fatal accidents that occurred in the USA from 2005 to 2018 and performed bow-tie analyses using the final reports published by the Mine Safety and Health Administration. The analyses explore the context of the accidents with a focus on the initiating event, event outcome, hazards present, and possible preventative and mitigative controls. Overall, the vast majority of the accidents resulted in a haul truck colliding with the environment, and the majority of these events were initiated by loss of situational awareness or loss of control. The majority of the hazards were related to design and organizational controls. The results of this study suggest a need to investigate operator decision-making and organizational controls and to focus on improving design and operation controls such as mine design and operational procedures.

Work-related factors, cognitive skills, unsafe behavior and safety incident involvement among emergency medical services crew members: relationships and indirect effects

Objectives. This study examines relationships between work-related factors - stress and fatigue, cognitive skills - situation awareness and cognitive flexibility, unsafe behavior and safety incident involvement among emergency medical services (EMS) crew members, and whether cognitive skills and unsafe behavior together indirectly affect the relationship between work-related factors and safety incident involvement. Methods. A sample of 131 EMS crew members working in ground ambulances (physicians, paramedics, ambulance drivers) completed self-report questionnaires. Results. The correlation analysis showed significant positive interrelationships between work-related factors, unsafe behavior and safety incident involvement, and that cognitive skills were significantly negatively related to these variables. The multiple indirect effects analysis revealed significant indirect effects of both work-related factors on safety incident involvement through situation awareness and unsafe behavior, but not through cognitive flexibility. Conclusion. In terms of reducing the number of EMS provider and patient safety incidents, the findings suggest the importance of reducing stress and fatigue in EMS crew members, improving their cognitive skills, in particular situation awareness, and supporting their safety compliance behavior.

Evaluation of Fatigue and Workload among Workers Conducting Complex Manual Assembly in Manufacturing

OCCUPATIONAL APPLICATIONSWe conducted a study to evaluate fatigue and workload among workers performing complex assembly tasks. We investigate several predictors of fatigue, including subjective workload estimates, sleep duration, the shift being worked, and production levels. High levels of fatigue were reported in one-third of the shifts evaluated. The main predictors of high fatigue were workload estimates, working evening shifts, and baseline fatigue. Among the six dimensions of workload, only mental demand and frustration were predictors of high fatigue. Mental demand was also rated highest. Participants reported less than seven hours of sleep in 60% of the nights evaluated. These results suggest that managers and supervisors should consider cognitive workload as a key contributing factor to fatigue in complex manual assembly. Similarly, work schedule planning should consider shift duration, start times, and end times, because of the negative influence on fatigue and the potential disruptions on sleep among workers.

Association between circadian disruption and diseases: A narrative review

Circadian rhythms play an important role in a wide range of human physiology and pathology. Individuals increasingly experience situations such as night-shift work schedules, likely leading to circadian disruption. Recent studies have also demonstrated that patients with other diseases often show symptoms of circadian disruption as manifested by the sleep-wake cycle and other biological rhythms. Circadian disruption often results in changes to the phase, period, and amplitude of the sleep-wake cycle, melatonin rhythm, and core body temperature. Several cardiometabolic, psychiatric, and neurodegenerative diseases are closely related to circadian disruption. Several interventions are also available, including phototherapy, exogenous melatonin, and exercise. The cumulative findings suggest that circadian disruption can increase risk for some cardiometabolic diseases. Circadian disruption also acts as a concomitant symptom of several psychiatric and neurodegenerative diseases. More attention should be paid to evaluating the impact of circadian disruption on these related diseases, as well as the benefits of the mitigation interventions for both circadian disruption and related diseases.

Abnormal Sleep, Circadian Rhythm Disruption, and Delirium in the ICU: Are They Related?

Delirium is a syndrome characterized by acute brain failure resulting in neurocognitive disturbances affecting attention, awareness, and cognition. It is highly prevalent among critically ill patients and is associated with increased morbidity and mortality. A core domain of delirium is represented by behavioral disturbances in sleep-wake cycle probably related to circadian rhythm disruption. The relationship between sleep, circadian rhythm and intensive care unit (ICU)-acquired delirium is complex and likely bidirectional. In this review, we explore the proposed pathophysiological mechanisms of sleep disruption and circadian dysrhythmia as possible contributing factors in transitioning to delirium in the ICU and highlight some of the most relevant caveats for understanding the relationship between these complex phenomena. Specifically, we will (1) review the physiological consequences of poor sleep quality and efficiency; (2) explore how the neural substrate underlying the circadian clock functions may be disrupted in delirium; (3) discuss the role of sedative drugs as contributors to delirium and chrono-disruption; and, (4) describe the association between abnormal sleep-pathological wakefulness, circadian dysrhythmia, delirium and critical illness. Opportunities to improve sleep and readjust circadian rhythmicity to realign the circadian clock may exist as therapeutic targets in both the prevention and treatment of delirium in the ICU. Further research is required to better define these conditions and understand the underlying physiologic relationship to develop effective prevention and therapeutic strategies.

Multiple caffeine doses maintain vigilance, attention, complex motor sequence expression, and manual dexterity during 77 hours of total sleep deprivation

Sleep deprivation (SD) and fatigue have detrimental effects on performance in operational settings. Few studies have investigated the cumulative effects of SD and fatigue on performance under heavy workload demands. Therefore, we investigated the efficacy of multiple repeated doses of caffeine as a countermeasure to SD and fatigue during 77 h total SD (TSD) during the early morning hours. Twenty-three males and females, 18 – 35 years of age, who identified as moderate caffeine consumers completed the Psychomotor Vigilance Task (PVT) 141 times during the experimental test period. Caffeine was administered in a multi-dose paradigm over three nights without sleep. Participants received either caffeine (200 mg) or placebo at the beginning of each 2-h test block from 0100 – 0900 (800 mg total per night). While PVT speed declined for both groups across all 3 nights, the caffeine group consistently out-performed the placebo group. Caffeine maintained attentiveness (1-5 s lapses) on night 1, but this advantage was lost on nights 2 and 3. Caffeine outperformed placebo for responsive lapses (5-9 s lapses) across all three nights, but caffeine performance was still notably worse than at baseline. Prolonged non-responsive lapses (beyond 10 s) were only reduced by caffeine on night 2. Caffeine was more effective than placebo across all nights at sustaining completion speed of a complex motor sequence task and a manual coordination task. Essentially, caffeine is an effective countermeasure for SD, as it mitigates declines in speed and failures to respond, and sustains motor planning and coordination. However, caffeine does not restore normal functioning during SD and cannot be considered as a replacement for sleep.

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Compared caffeine versus placebo during extreme sleep deprived monotony.

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Caffeine improved psychomotor vigilance speed and reduced lapses of all durations.

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Caffeine did not maintain normal performance after the first night of sleep loss.

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Caffeine sustained motor planning and coordination better than placebo.

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Caffeine mitigates sleep loss deficits but does not sustain performance at normal.

Sleep deprivation, vigilant attention, and brain function: a review

Vigilant attention is a major component of a wide range of cognitive performance tasks. Vigilant attention is impaired by sleep deprivation and restored after rest breaks and (more enduringly) after sleep. The temporal dynamics of vigilant attention deficits across hours and days are driven by physiologic, sleep regulatory processes-a sleep homeostatic process and a circadian process. There is also evidence of a slower, allostatic process, which modulates the sleep homeostatic setpoint across days and weeks and is responsible for cumulative deficits in vigilant attention across consecutive days of sleep restriction. There are large inter-individual differences in vulnerability to sleep loss, and these inter-individual differences constitute a pronounced human phenotype. However, this phenotype is multi-dimensional; vulnerability in terms of vigilant attention impairment can be dissociated from vulnerability in terms of other cognitive processes such as attentional control. The vigilance decrement, or time-on-task effect-a decline in performance across the duration of a vigilant attention task-is characterized by progressively increasing response variability, which is exacerbated by sleep loss. This variability, while crucial to understanding the impact of sleep deprivation on performance in safety-critical tasks, is not well explained by top-down regulatory mechanisms, such as the homeostatic and circadian processes. A bottom-up, neuronal pathway-dependent mechanism involving use-dependent, local sleep may be the main driver of response variability. This bottom-up mechanism may also explain the dissociation between cognitive processes with regard to trait vulnerability to sleep loss.