Caffeine protects against increased risk-taking propensity during severe sleep deprivation

The effects of sleep deprivation on risky decision making

Sleep deprivation stands as a major threat to both physical and mental well-being, disrupting normal work and life. Given the ubiquity of risky decision making, it is crucial to comprehend how individuals make risky decisions when sleep-deprived. Although research on the effects of sleep deprivation on risky decision making has increased in recent years, it remains limited and lacks a unified conclusion. The current review attempted to elucidate the effects of sleep deprivation on risky decision making in healthy adults and clarify the regulatory mechanisms. The review showed that sleep deprivation had complex effects on risky decision making; that is, whether sleep deprivation led to riskier or more conservative decision-making behavior depended on factors such as sex, gain-loss frame, use of psychotropic drugs, time interval of sleep elimination, duration of sleep deprivation, and others. Additionally, the complexity of these effects might partly arise from the use of different tasks to measure risk-taking behavior. The review also discussed some limitations of existing research and put forth practical recommendations for future studies, aiming to resolve inconsistencies in the effects of sleep deprivation on risky decision making and enhance the ecological validity of conclusions.

Sleep Fragmentation Results in Novel Set-shifting Decrements in GCR-exposed Male and Female Rats

The prolonged exposure to multiple spaceflight stressors during long-duration missions to the Moon and Mars will be challenging to the physical and mental health of the astronauts. Ground-based studies have reported that attentional set-shifting task (ATSET) performance is impaired after space radiation (SR) exposure. At certain times during deep-space missions, astronauts will likely have to contend with the combined impacts of SR and sleep perturbation. In rats, poor quality, fragmented sleep adversely impacts performance in multiple cognitive tasks, including the ATSET task. While both SR and sleep perturbations independently cause cognitive performance deficits, the incidence, severity and exact nature of those decrements following combined exposure to these flight stressors is largely unknown. This study established the impact that a single night of fragmented sleep has on ATSET performance in both male and female rats exposed to 10 cGy of galactic cosmic ray simulation (GCRsim). The GCRsim beam is a complex beam that mimics the mass and energy spectra of the SR particles that an astronaut will be exposed to within the spacecraft. Rats that had no obvious ATSET performance decrements when normally rested were subjected to fragmented sleep and their ATSET performance reassessed. Sleep fragmentation resulted in significant ATSET performance decrements in GCRsim-exposed rats, with specific performance decrements being observed in stages where attention or cue shifting is extensively used. Performance decrements in these stages are rarely observed after SR exposure. While both male and female rats exhibited latent sleep-related performance decrements, these were sex dependent, with male and female rats exhibiting different types of performance decrements (either reduced processing speed or task completion efficiency) in different stages of the ATSET task. This study suggests that SR-induced cognitive impairment may not be fully evident in normally rested rats, with an underestimation of both the incidence and nature of performance decrements that could occur when multiple space flight stressors are present. These data suggest that that there may be synergistic interactions between multiple space flight stressors that may not be easily predicted from their independent actions.

Poorer decision making among college students during the COVID-19 pandemic: Evidence for "pandemic-brain"

OBJECTIVE

Did living through the COVID-19 pandemic cause healthy college students to experience "pandemic-brain," a phenomenon characterized by difficulties with various cognitive abilities? Did students shift from deliberative to more impulsive decision making?

PARTICIPANTS

We compared a pre-pandemic sample of 722 undergraduate students to 161 undergraduate students recruited in Fall 2020, during the COVID-19 pandemic.

METHOD

We compared scores on the Adult Decision Making Competence scale among participants who completed the task pre-pandemic or across two time points in Fall 2020, during the pandemic.

RESULTS

Decision making was less consistent and more reliant on gain/loss framing during the pandemic compared to pre-pandemic, but college students were no less confident in their decisions. No significant changes in decision making occurred during the pandemic.

CONCLUSIONS

These decision making changes could increase the risk of making an impulsive choice with negative health consequences affecting demands on student health centers and imperiling learning environments.

Ad libitum caffeine consumption, cognitive performance, and sleep in special forces soldiers during a 96-h combat exercise

Introduction

This observational study investigated the effects of sleep deprivation and ad libitum caffeine consumption on cognitive performance, risk behavior, and mood among 28 Israeli Special Forces (SF) soldiers (mean age: 20.57 ± 0.92 years) during a 96-hour combat exercise.

Methods

Actigraphy was used to monitor sleep and activity; cognitive function, risk-taking propensity, mood states, and self-reported sleepiness were assessed using the Psychomotor Vigilance Task (PVT), Evaluation of Risks Scale (EVAR), Profile of Mood States (POMS), Karolinska Sleepiness Scale (KSS); and caffeine consumption by questionnaire at 0, 50, and 96 hours. For analyses, participants were divided into Low (<400 mg) and High (≥400 mg) caffeine consumption groups.

Results

The soldiers hiked 108.5 ± 0.52 km and slept for 12.7 ± 0.5 h, with a notable transition from multiple short sleep epochs in the initial 50 hours to a consolidated 5-hour sleep period subsequently. In the High caffeine group, PVT reaction time was faster (p = 0.024) compared to the Low caffeine group, with fewer premature response errors (p = 0.026). However, this group showed increased risk-taking (p = 0.037), particularly reduced Self-Control (p = 0.010). No significant impact of ad libitum caffeine intake on mood was observed. However, degradation over the course of the exercise in both groups in mood states, including anger, fatigue, tension, and vigor, was noted (p < 0.05). KSS scores increased significantly at 50 and 96 h (p < 0.001).

Discussion

These results suggest that while caffeine enhances cognitive function, its ad libitum consumption did not consistently improve these measures in this cohort of SF soldiers. The study highlights the complex relationship between sleep deprivation and caffeine intake and their combined effects on soldiers' cognitive and behavioral functions, indicating a need for evidence-based caffeine use guidelines for using caffeine in military settings.

The effects of sound in the Balloon Analogue Risk Task

In this study, we examined the effects of pairing sounds with positive and negative outcomes in the Balloon Analogue Risk Task (BART). A number of published studies using the BART incorporate sounds into the task, where a slot machine or cash register sound is produced when rewards are collected and a popping sound is produced when balloons pop. However, some studies do not use sound, and other studies do not specify whether sound was used. Given that sensory information contributes to the intensity of experiences, it is possible that outcome-related sounds in the BART influence risk-taking behaviors, and inconsistent use of sounds across the many BART variations may affect how results are interpreted. Therefore, the purpose of this study was to investigate the effects of sounds paired with outcomes in the BART, and whether the presence or valence of a sound would systematically alter participants' risk-taking. Across two experiments using Bayesian censored regressions, we show that sounds, regardless of the outcomes they were paired with or their valence, did not affect risk-taking in an adult, non-clinical sample. We consider the implications of these results within methodological and theoretical contexts and encourage researchers to continue dissociating the role of auditory stimuli in feedback processing and subsequent responding.

Acute caffeine differently affects risk-taking and the expression of BDNF and of adenosine and opioid receptors in rats with high or low anxiety-like behavior

Anxiety disorders are common psychiatric conditions with a partially elucidated neurobiology. Caffeine, an unspecific adenosine receptor antagonist, is a common psychostimulant with anxiogenic effects in sensitive individuals. High doses of caffeine produce anxiety-like behavior in rats but it is not known if this is specific for rats with high baseline anxiety-like behavior. Thus, the aim of this study was to investigate general behavior, risk-taking, and anxiety-like behavior, as well as mRNA expression (adenosine A2A and A1, dopamine D2, and, μ, κ, δ opioid, receptors, BDNF, c-fos, IGF-1) in amygdala, caudate putamen, frontal cortex, hippocampus, hypothalamus, after an acute dose of caffeine. Untreated rats were screened using the elevated plus maze (EPM), giving each rat a score on anxiety-like behavior based on their time spent in the open arms, and categorized into a high or low anxiety-like behavior group accordingly. Three weeks after categorization, the rats were treated with 50 mg/kg caffeine and their behavior profile was studied in the multivariate concentric square field (MCSF) test, and one week later in the EPM. qPCR was performed on selected genes and corticosterone plasma levels were measured using ELISA. The results demonstrated that the high anxiety-like behavior rats treated with caffeine spent less time in risk areas of the MCSF and resituated towards the sheltered areas, a behavior accompanied by lower mRNA expression of adenosine A2A receptors in caudate putamen and increased BDNF expression in hippocampus. These results support the hypothesis that caffeine affects individuals differently depending on their baseline anxiety-like behavior, possibly involving adenosine receptors. This highlights the importance of adenosine receptors as a possible drug target for anxiety disorders, although further research is needed to fully elucidate the neurobiological mechanisms of caffeine on anxiety disorders.

Sleep duration moderates the associations between immune markers and corticolimbic function during stress in adolescents

Adolescence is characterized by biological changes in hormonal and circadian systems that, with concurrent psychosocial changes, result in increased sleep disturbances and stress sensitivity. Sleep disturbance has been associated with heightened stress sensitivity and elevated levels of inflammation in adults and adolescents, yet the neural correlates are unknown in adolescents. The current study investigated whether and how individual differences in peripheral immune markers (IL-6, TNF-α) related to neural response to stress in adolescents and whether these immune-brain associations were moderated by adolescents' sleep duration. Thirty-seven adolescents (14-15 years) who met quality control criteria for fMRI reported daily sleep duration for 7 days and performed a fMRI stressor task. A subsample of 23 adolescents additionally provided blood samples that were assayed for inflammatory markers using a multiplex assay. Results revealed that average sleep duration moderated associations between TNF-α and medial frontolimbic circuitry (amygdala, medial prefrontal cortex) during the stressor task such that, among adolescents who reported shorter sleep duration, higher levels of TNF-α were associated with greater deactivation in those regions during stress, which was associated with greater self-reported anxiety. These findings suggest that insufficient sleep duration coupled with greater levels of peripheral inflammation may promote a neural profile characterized by alterations in frontolimbic circuitry during stress, which can exacerbate sleep disturbances and/or peripheral inflammation.

Predicting and mitigating fatigue effects due to sleep deprivation: A review

The deleterious effects of insufficient sleep have been well-established in the literature and can lead to a wide range of adverse health outcomes. Some of the most replicated findings demonstrate significant declines in cognitive functions such as vigilance and executive attention, psychomotor and cognitive speed, and working memory. Consequently, these decrements often lead individuals who are in a fatigued state to engage in substandard performance on everyday tasks. In the interest of curtailing these effects, prior work has attempted to identify mechanisms that predict fatigue onset and develop techniques to mitigate its negative consequences. Nonetheless, these results are often confounded by variables such as an individual’s resistance to fatigue, sleep history, and unclear distinctions about whether certain performance decrements are present due to fatigue or due to other confounding factors. Similar areas of research have provided approaches to produce models for the prediction of cognitive performance decrements due to fatigue through the use of multi-modal recording and analysis of fatigue-related responses. Namely, gathering and combining response information from multiple sources (i.e., physiological and behavioral) at multiple timescales may provide a more comprehensive representation of what constitutes fatigue onset in the individual. Therefore, the purpose of this review is to discuss the relevant literature on the topic of fatigue-related performance effects with a special emphasis on a variety of physiological and behavioral response variables that have shown to be sensitive to changes in fatigue. Furthermore, an increasing reliance on sleep loss, meant to assist in meeting the demands of modern society, has led to an upsurge in the relevance of identifying dependable countermeasures for fatigued states. As such, we will also review methods for the mitigation of performance effects due to fatigue and discuss their usefulness in regulating these effects. In sum, this review aims to inspire future work that will create opportunities to detect fatigue and mitigate its effects prior to the onset of cognitive impairments.

Teacher Support Matters: The Effect of Self-Control Demands on Safety Behavior of Vocational High School Students in China

The safety behavior of vocational school students is worth noting. The current study is aimed to examine the effect of self-control demands on safety behavior. Drawing on the Self-Control Resource Model, we predict that self-control demands have a negative effect on safety behavior through ego depletion and perceived teacher support moderates the link among self-control demands, ego depletion, and safety behavior. A two-wave survey was conducted and 285 vocational students participated in our study. Mediation and moderated mediation modeling analyses were carried out. Results showed that ego depletion fully mediated the link between self-control demands and safety behavior. Moreover, perceived teacher support moderated the relationship between self-control demands, ego depletion and safety behavior; for students who perceived high levels of teacher support, the negative effect of self-control demands on safety behavior via ego depletion was insignificant, while for students who perceived low levels of teacher support, their negative effect was significant. The present study clarifies the effects of self-control demands on safety behavior through the resource depletion process and highlights the importance of teacher support in buffering the negative effect of self-control demands on workplace safety. Enhancing safety management, engaging in a resource recovery activity, and providing teacher support training are effective ways to maintain high levels of workplace safety.

Sleep and Athletic Performance: Impacts on Physical Performance, Mental Performance, Injury Risk and Recovery, and Mental Health: An Update

Sleep health is an important consideration for athletic performance. Athletes are at high risk of insufficient sleep duration, poor sleep quality, daytime sleepiness and fatigue, suboptimal sleep schedules, irregular sleep schedules, and sleep and circadian disorders. These issues likely have an impact on athletic performance via several domains. Sleep loss and/or poor sleep quality can impair muscular strength, speed, and other aspects of physical performance. Sleep issues can also increase risk of concussions and other injuries and impair recovery after injury. Cognitive performance is also impacted in several domains, including vigilance, learning and memory, decision making, and creativity.

Effects of the psychoactive compounds in green tea on risky decision-making

Epigallocatechin-3-gallate (EGCG) and caffeine are the two primary compounds found in green tea. While EGCG has anxiolytic and anti-inflammatory effects, its acute effects on cognition are not well understood. Furthermore, despite widespread green tea consumption, little is known about how EGCG and caffeine co-administration impacts behavior. Here, we investigated the effects of multiple doses of either EGCG or caffeine on a rat model of risk-taking. This was assessed using the risky decision-making task (RDT), in which rats choose between a small, well-tolerated reward and a large reward with escalating risk of mild footshock. Rats were tested in RDT after acute systemic administration of EGCG, caffeine or joint EGCG and caffeine. EGCG caused a dose-dependent reduction in risk-taking without affecting reward discrimination or task engagement. Caffeine did not impact risk-taking, but elevated locomotor activity and reduced task engagement at high doses. Finally, exposure to both EGCG and caffeine had no effect on risk-taking, suggesting that low-dose caffeine is sufficient to mask the risk-aversion caused by EGCG. These data suggest EGCG as a potential therapeutic treatment for psychological disorders that induce compulsive risky decision-making.

The relationship of caffeinated beverages with depressive symptoms and decision-making

BACKGROUND: Caffeine can affect depressive symptoms and decision-making. OBJECTIVE: This study aims to examine the relationship between caffeinated beverages consumption with depressive symptoms and decision-making styles. METHODS: This cross-sectional study was conducted with 432 adults working in office environment. The questionnaire consisting of individuals’ socio-demographic attributes, the frequency and the amount of caffeinated beverages consumption, the “Epidemiological Research Center-Depression (CES-D) Scale” and the “Decision-Making Styles Scale” were used. The frequency and amount of caffeinated beverages were determined using the food frequency questionnaire (FFQ). The participants were asked to choose which cup/mug they prefer to drink their caffeinated beverages and what amount they consume that beverage at a time. All the data were collected using online platforms. RESULTS: In the study, 76.7%of the participants were female and the mean age was 31.5±8.0 years. The average daily total caffeine intake of the participants was 425.8±461.4 mg and the total CES-D scale score was 17.7±11.2 points. It was found that as the amount of caffeine consumed increased, intuitive decision-making decreased and depressive symptoms increased (p <  0.05). In linear regression analysis, total caffeine consumption was found to be a significant predictor for the intuitive decision-making score (B: –0.151; p:0.002). When caffeine consumption is controlled, intuitive and rational decision making decreases with increasing depressive symptoms while addiction and avoidance decision making increased (p <  0.05). CONCLUSIONS: As a result, the amount of caffeine consumed daily was related to intuitive decision-making but did not effect depression. It has been observed that depressive symptoms affect decision-making styles in different ways. To our knowledge, our study is the first to examine the effects of caffeine consumption on depression and decision-making styles. Accordingly, future studies may focus on the link between caffeine consumption, depression, and decision-making styles in larger populations and the mechanisms that influence this relationship.

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 and Athletic Performance: Impacts on Physical Performance, Mental Performance, Injury Risk and Recovery, and Mental Health

Research has characterized the sleep of elite athletes and attempted to identify factors associated with athletic performance, cognition, health, and mental well-being. Sleep is a fundamental component of performance optimization among elite athletes, yet only recently embraced by sport organizations as an important part of training and recovery. Sleep plays a crucial role in physical and cognitive performance and is an important factor in reducing risk of injury. This article aims to highlight the prevalence of poor sleep, describe its impacts, and address the issue of sport culture surrounding healthy sleep.

Chronic sleep loss and risk-taking behavior: Does the origin of sleep loss matter?

Background: Many adolescents and young adults get insufficient sleep. A link between sleep loss and risk-taking behavior has been consistently found in the literature, but surprisingly, the role played by the origin of sleep loss in this link has never been investigated. Sleep loss can be voluntary (instead of sleeping, a significant amount of time is devoted to other activities) or involuntary (caused by a sleep disorder, for example, insomnia). The aim of this research was to investigate whether both types of sleep loss are associated to the same extent with risky behavior. Participants: Five hundred thirty-six university students between 19 and 25 years old participated in this study. Three groups were selected: participants with voluntary sleep loss, participants with insomnia, and normal sleepers. Methods: We assessed risk-taking behavior in virtual driving situations, as well as drinking habits in terms of quantity and frequency. To further explore the differences between the groups, we also measured sensation seeking, a personality trait related to risk-taking behavior. Results: Compared to participants with insomnia and normal sleepers, participants with voluntary sleep loss take more risks in dangerous driving situations, drink more alcohol, and have higher disinhibition scores on the Sensation-Seeking Scale. On the other hand, no such differences were found between participants with insomnia and normal sleepers, suggesting that sleep loss is not always associated with risk taking. Conclusions: Whether sleep loss is associated with risk-taking behavior or not could depend on the origin of sleep loss and the underlying personality traits.

Framing effect, probability distortion, and gambling tendency without feedback are resistant to two nights of experimental sleep restriction

Several studies suggest that sleep deprivation affects risky decision making. However, most of these are confounded by feedback given after each decision, indicating that decisions may be based on suboptimal feedback-learning rather than risk evaluation. Furthermore, few studies have investigated the effect of sleep loss on aspects of prospect theory, specifically the framing effect and probability distortion. In this within-subjects design, 25 people had (i) two nights of an 8 h sleep opportunity, and (ii) two nights of a 4 h sleep opportunity, in a counter-balanced order. Following the two nights, they performed a gambling task with no immediate feedback; for each round, they could either gamble for a full amount, or take a settlement framed as a gain or a loss for part of the amount. Sleep restriction did not significantly affect the tendency to gamble, the framing effect, or probability distortion, as compared to normal sleep. These results indicate that two nights of sleep restriction affects neither general gambling tendency, nor two of the main predictions of prospect theory. This resilience may be due to a less extreme sleep loss than in previous studies, but also indicates that learning components and risk biases should be separated when assessing the effect of sleep loss on risky behaviour.

Cognitive function and mood at high altitude following acclimatization and use of supplemental oxygen and adaptive servoventilation sleep treatments

Impairments in cognitive function, mood, and sleep quality occur following ascent to high altitude. Low oxygen (hypoxia) and poor sleep quality are both linked to impaired cognitive performance, but their independent contributions at high altitude remain unknown. Adaptive servoventilation (ASV) improves sleep quality by stabilizing breathing and preventing central apneas without supplemental oxygen. We compared the efficacy of ASV and supplemental oxygen sleep treatments for improving daytime cognitive function and mood in high-altitude visitors (N = 18) during acclimatization to 3,800 m. Each night, subjects were randomly provided with ASV, supplemental oxygen (SpO2 > 95%), or no treatment. Each morning subjects completed a series of cognitive function tests and questionnaires to assess mood and multiple aspects of cognitive performance. We found that both ASV and supplemental oxygen (O2) improved daytime feelings of confusion (ASV: p < 0.01; O2: p < 0.05) and fatigue (ASV: p < 0.01; O2: p < 0.01) but did not improve other measures of cognitive performance at high altitude. However, performance improved on the trail making tests (TMT) A and B (p < 0.001), the balloon analog risk test (p < 0.0001), and the psychomotor vigilance test (p < 0.01) over the course of three days at altitude after controlling for effects of sleep treatments. Compared to sea level, subjects reported higher levels of confusion (p < 0.01) and performed worse on the TMT A (p < 0.05) and the emotion recognition test (p < 0.05) on nights when they received no treatment at high altitude. These results suggest that stabilizing breathing (ASV) or increasing oxygenation (supplemental oxygen) during sleep can reduce feelings of fatigue and confusion, but that daytime hypoxia may play a larger role in other cognitive impairments reported at high altitude. Furthermore, this study provides evidence that some aspects of cognition (executive control, risk inhibition, sustained attention) improve with acclimatization.

Sleepiness and Behavioral Risk-Taking: Do Sleepy People Take More or Less Risk?

BACKGROUND

Although sleep loss has been implicated in risk-taking behavior, it is unclear how individuals' current propensity to fall asleep, known as sleepiness, influences risk-taking. Because sleepiness is not only driven by recent sleep but also by factors such as circadian rhythm and current stimulation, it may be an important contributor to risk-taking as it reflects the more immediate sleep-wake state.

PARTICIPANTS

One hundred thirty participants were recruited from a large Midwestern U.S. university.

METHODS

Participants completed a short personality survey, reported their current sleepiness on the Stanford Sleepiness Scale, and then completed the Balloon Analog Risk Task, a computerized risk-taking measure in which participants earned real money for their performance.

RESULTS

There was little support for a linear relation between sleepiness and risk-taking, but the evidence indicated a robust curvilinear relation. Even after controlling for important individual differences in sleep and risk-taking, participants who were moderately sleepy took longer to complete the risk-taking task, pumped balloons more, and exploded more balloons than those who were either low or high on sleepiness.

CONCLUSIONS

The curvilinear relation between sleepiness and risk-taking sheds light on inconsistencies in prior findings linking sleepiness and sleep loss to risk-taking behavior. Moreover, current sleepiness appears to have unique implications for risk-taking.

Two days of calorie deprivation impairs high level cognitive processes, mood, and self-reported exertion during aerobic exercise: A randomized double-blind, placebo-controlled study

Military personnel and emergency responders perform cognitively-demanding tasks during periods of sustained physical exertion and limited caloric intake. Cognitive function is preserved during short-term caloric restriction, but it is unclear if preservation extends to combined caloric restriction and physical exertion. According to the "reticular-activating hypofrontality" model, vigorous exertion impairs prefrontal cortex activity and associated functions. This double-blind, placebo-controlled, crossover study examined cognitive function during sustained exertion while volunteers were calorically-deprived. Twenty-three volunteers were calorie-depleted for two days on one occasion and fully-fed on another. They completed intermittent bouts of exercise at 40-65% VO_2peak while prefrontal cortex-dependent tasks of cognitive control, mood, and perceived exertion were assessed. Calorie deprivation impaired accuracy on the task-switching task of set-shifting (p < .01) and decreased sensitivity on the go/no-go task of response inhibition (p < .05). Calorie deprivation did not affect risk taking on the Rogers risk task. During exercise, calorie deprivation, particularly on day 2, increased perceived exertion (p < .05) and impaired mood states of tension, depression, anger, vigor, fatigue, and confusion (all p < .01). Physical exertion during severe calorie deprivation impairs cognitive control, mood, and self-rated exertion. Reallocation of cerebral metabolic resources from the prefrontal cortex to structures supporting movement may explain these deficits.

Blunted neural response to gains versus losses associated with both risk-prone and risk-averse behavior in a clinically diverse sample

Reduced responsiveness to reward has been associated with both risk-prone and risk-averse behavior, common features of externalizing and internalizing psychopathology, respectively. Thus, evidence has suggested a potential quadratic relationship (i.e., inverted U) between reward sensitivity and risk-taking propensity. Blunted response to reward compared to loss may therefore demonstrate transdiagnostic utility as it relates to different patterns of maladaptive risk behavior. The current study sought to disentangle the relationship between risk and reward in a clinically diverse sample. In a sample of 210 adults (aged 18-30), the RewP (an ERP indexing differentiation between rewards and losses) was measured during a monetary guessing game, and risk-taking propensity was measured with a behavioral task (i.e., BART) that simulates real-world risk taking. Participants also completed clinical assessments to assess for lifetime psychopathology. Results indicated that there was no linear association between the RewP and risk-taking propensity; however, there was a significant quadratic relationship. Thus, a reduced sensitivity to reward receipt was associated with both risk-prone and risk-averse behavior. There was also a significant quadratic relationship between the RewP and money won during the BART, indicating that being too risk prone or risk averse is disadvantageous and leads to missed reward. Overall, these findings suggested that blunted neural differentiation between gains and losses may contribute to deficits in effectively weighing reward and loss and result in maladaptive risk-taking behavior. These findings support continued examination of reward dysfunction dimensionally in order to better characterize behavioral profiles implicated in clinical phenotypes.

Effects of caffeine on sleep quality and daytime functioning

Caffeine (particularly in the form of coffee) is one of the most widely consumed stimulants in the world, with 90% of American adults consuming caffeine-infused beverages almost daily. While there is substantial evidence that caffeine enhances performance, caffeine withdrawal leads to deficits at both the individual (eg, cognitive, emotional, and behavioral processes) and societal (eg, increases in work accidents) level. Scholars for some time have considered that the supposed psychoactive benefits of caffeine may be the result of the mere reversal of deleterious effects of caffeine withdrawal, rather than a net benefit of caffeine ingestion. In this integrative review, we examine evidence illuminating the relationship between caffeine consumption and subsequent quality and quantity of nighttime rest. Secondly, we consider evidence as to whether performance deficits caused by sleep deprivation linked to caffeine can be reversed by caffeine consumption during the subsequent daytime period. Finally, we consider how these two stages can be reconciled in a single model that enables calculation of the net caffeine effect on daytime functioning. The literature highlights a range of positive impacts of caffeine consumption on both physical and cognitive functioning. There are also a number of factors that complicate any conclusions that can be drawn regarding the potential of caffeine to improve performance. Most critically, performance improvements the next day may simply be a result of the reversal of caffeine withdrawal. Animal studies and well-controlled human studies involving high habitual and low habitual users tend to confirm a "net benefit" for caffeine use. Further research, particularly with (necessarily rare) caffeine-naive populations, is required to elucidate the complexities of the relationship between caffeine, sleep, and daytime functioning. However, the convenience of accessing caffeine compared to ensuring adequate restorative sleep means that caffeine has applied advantages that are likely to see its use as a performance "enhancing" substance persist.

Le syndrome postgarde de nuit chez les médecins urgentistes : caractéristiques et facteurs influençants

Introduction : Les urgentistes connaissent une privation de sommeil en lendemain de garde. Beaucoup ont des perceptions ou des comportements inhabituels que nous appelons syndrome post-garde de nuit (PGN). L’objectif principal était de caractériser le syndrome PGN des urgentistes. Les objectifs secondaires étaient d’établir une note évaluant le syndrome PGN et de déterminer les facteurs influençant ce syndrome PGN.

Méthode : Étude prospective de cohorte, observationnelle, multicentrique, auprès des urgentistes du Gard et de l’Hérault entre janvier et juin 2017. Deux questionnaires informatiques anonymes étaient diffusés aux structures d’urgences du Gard et de l’Hérault. En journée normale, hors sortie de garde, un questionnaire colligeait les symptômes ressentis habituellement en lendemain de garde, à coter entre 0 et 10. En sortie de garde, un autre questionnaire s’intéressait au ressenti de la garde réalisée et aux caractéristiques de cette garde. Les médecins étaient encouragés à répondre aux deux questionnaires.

Résultats : Cent treize médecins (45 %) ont répondu, 67 (59 %) à distance d’une garde et 46 (41 %) en post-garde immédiat. Le syndrome PGN comprend des symptômes somatiques (échelle visuelle analogique (EVA) = 5 [2–8]), comportementaux (EVA = 7 [3–8]), liés à l’humeur (EVA = 7[5–8]) et psychiques (EVA = 6 [4–8]). Ces symptômes en post-garde immédiat étaient ressentis de manière moins importante que lorsque décrit à distance (respectivement p = 0,001, p <0,001, p < 0,001, p = 0,002). Les gardes de SMUR (service mobile d’urgence et de réanimation) et de traumatologie étaient associées à un syndrome PGN moins marqué (respectivement p =0,035 et p = 0,02) que les gardes des filières médico-chirurgicales.

Conclusion : Il s’agit de la première évaluation du syndrome PGN chez les urgentistes français. Les symptômes en sont moins importants en post-garde immédiat. Les gardes de traumatologie et de SMUR semblent mieux tolérées.

Neurophysiological differences in the adolescent brain following a single night of restricted sleep - A 7T fMRI study

Sleep deprivation in youth has garnered international attention in recent years, as correlational studies have demonstrated significant relationships between lack of sleep and detrimental behavioral and academic outcomes. However, no study to date has systematically examined the neurophysiological consequences of a single night of sleep restriction (i.e., 4 h) in adolescents using ultra-high field functional neuroimaging. Much of what we know regarding the neural consequences of sleep deprivation has come from the adult literature, and among those studies, the majority use region of interest (ROI) approaches, thus disregarding the dynamic mechanisms that may subserve the behavioral effects of sleep restriction. Leveraging a crossover within-subjects design, we demonstrate that pivotal brain regions involved in the default mode and limbic regulatory centers have disrupted functioning following a night of restricted sleep compared to a night of "normal sleep". Specifically, a normal night (i.e., 8 h) of sleep led to increased global and local efficiency of bilateral amygdala, and less efficiency in the posterior cingulate, as measured by graph theory, compared to a night of sleep restriction. Furthermore, aberrant functional connectivity patterns were identified in key fronto-limbic circuitry, suggesting a potential pathophysiological mechanism underlying the widespread effects of sleep deprivation in youth.

Sleep Deprivation Promotes Habitual Control over Goal-Directed Control: Behavioral and Neuroimaging Evidence

Sleep is one of the most fundamental processes of life, playing an important role in the regulation of brain function. The long-term lack of sleep can cause memory impairments, declines in learning ability, and executive dysfunction. In the present study, we evaluated the effects of sleep deprivation on instrumental learning behavior, particularly goal-directed and habitual actions in humans, and investigated the underlying neural mechanisms. Healthy college students of either gender were enrolled and randomly divided into sleep deprivation group and sleep control group. fMRI data were collected. We found that one night of sleep deprivation led to greater responsiveness to stimuli that were associated with devalued outcomes in the slips-of-action test, indicating a deficit in the formation of goal-directed control and an overreliance on habits. Furthermore, sleep deprivation had no effect on the expression of acquired goal-directed action. The level of goal-directed action after sleep deprivation was positively correlated with baseline working memory capacity. The neuroimaging data indicated that goal-directed learning mainly recruited the ventromedial PFC (vmPFC), the activation of which was less pronounced during goal-directed learning after sleep deprivation. Activation of the vmPFC during goal-directed learning during training was positively correlated with the level of goal-directed action performance. The present study suggests that people rely predominantly on habits at the expense of goal-directed control after sleep deprivation, and this process involves the vmPFC. These results contribute to a better understanding of the effects of sleep loss on decision-making.SIGNIFICANCE STATEMENT Understanding the cognitive consequences of sleep deprivation has become extremely important over the past half century, given the continued decline in sleep duration in industrialized societies. Our results provide novel evidence that goal-directed action may be particularly vulnerable to sleep loss, and the brain mechanism underlying this effect was explored. Elucidation of the effects of sleep deprivation on decision-making will deepen our understanding of the function of sleep, emphasizing the role of sleep in cognitive impairments and mental health.

Insufficient sleep: Enhanced risk-seeking relates to low local sleep intensity

OBJECTIVES

Chronic sleep restriction is highly prevalent in modern society and is, in its clinical form, insufficient sleep syndrome, one of the most prevalent diagnoses in clinical sleep laboratories, with substantial negative impact on health and community burden. It reflects every-day sleep loss better than acute sleep deprivation, but its effects and particularly the underlying mechanisms remain largely unknown for a variety of critical cognitive domains, as, for example, risky decision making.

METHODS

We assessed financial risk-taking behavior after 7 consecutive nights of sleep restriction and after 1 night of acute sleep deprivation compared to a regular sleep condition in a within-subject design. We further investigated potential underlying mechanisms of sleep-loss-induced changes in behavior by high-density electroencephalography recordings during restricted sleep.

RESULTS

We show that chronic sleep restriction increases risk-seeking, whereas this was not observed after acute sleep deprivation. This increase was subjectively not noticed and was related to locally lower values of slow-wave energy during preceding sleep, an electrophysiological marker of sleep intensity and restoration, in electrodes over the right prefrontal cortex.

INTERPRETATION

This study provides, for the first time, evidence that insufficient sleep restoration over circumscribed cortical areas leads to aberrant behavior. In chronically sleep restricted subjects, low slow-wave sleep intensity over the right prefrontal cortex-which has been shown to be linked to risk behavior-may lead to increased and subjectively unnoticed risk-seeking. Ann Neurol 2017;82:409-418.

Ovarian hormones, sleep and cognition across the adult female lifespan: An integrated perspective

Loss of ovarian function in women is associated with sleep disturbances and cognitive decline, which suggest a key role for estrogens and/or progestins in modulating these symptoms. The effects of ovarian hormones on sleep and cognitive processes have been studied in separate research fields that seldom intersect. However, sleep has a considerable impact on cognitive function. Given the tight connections between sleep and cognition, ovarian hormones may influence selective aspects of cognition indirectly, via the modulation of sleep. In support of this hypothesis, a growing body of evidence indicates that the development of sleep disorders following menopause contributes to accelerated cognitive decline and dementia in older women. This paper draws from both the animal and human literature to present an integrated view of the effects of ovarian hormones on sleep and cognition across the adult female lifespan.

Sleep and obesity risk in adults: possible mechanisms; contextual factors; and implications for research, intervention, and policy

Obesity is a major public health problem among US adults. Insufficient sleep and sleep disorders are prevalent and may contribute to the public health problem of obesity. This review addresses several key questions regarding sleep and obesity in adults, including the following: (1) What constitutes adequate sleep in adults? (2) What are the consequences of inadequate sleep in adults? (3) What factors influence sleep in adults? (4) How can adults improve their sleep? (5) How can we implement these in adults? (6) How can these issues be addressed in future research and policy decisions? Although a comprehensive review of all of these is beyond the scope of this article, this review brings these concepts together toward a discussion of the role of sleep in the health of US adults.

Optimizing sleep to maximize performance: implications and recommendations for elite athletes

Despite a growing body of literature demonstrating a positive relationship between sleep and optimal performance, athletes often have low sleep quality and quantity. Insufficient sleep among athletes may be due to scheduling constraints and the low priority of sleep relative to other training demands, as well as a lack of awareness of the role of sleep in optimizing athletic performance. Domains of athletic performance (e.g., speed and endurance), neurocognitive function (e.g., attention and memory), and physical health (e.g., illness and injury risk, and weight maintenance) have all been shown to be negatively affected by insufficient sleep or experimentally modeled sleep restriction. However, healthy adults are notoriously poor at self-assessing the magnitude of the impact of sleep loss, underscoring the need for increased awareness of the importance of sleep among both elite athletes and practitioners managing their care. Strategies to optimize sleep quality and quantity in athletes include approaches for expanding total sleep duration, improving sleep environment, and identifying potential sleep disorders.

Partial sleep deprivation impacts impulsive action but not impulsive decision-making

Sleep deprivation may lead to increased impulsivity, however, previous literature has focused on examining effects of total sleep deprivation (TSD) rather than the more common condition, partial sleep deprivation (PSD) or 'short sleep'. Moreover, it has been unclear whether PSD impacts impulse-related cognitive processes, and specifically if it differentially affects impulsive action versus impulsive decision-making. We sought to determine if short compared to long sleep (6 vs. 9h/night) impacts impulsive action via behavioral inhibition (Go/No-Go), and/or impulsive decision-making processes of risk taking (Balloon Analogue Risk Task [BART]) and preferences for immediate over delayed rewards (Delay Discounting). In a within-subject design, 34 participants (71% female, mean age=37.0years, SD=10.54) were assigned to four consecutive nights of 6h/night (short sleep) and 9h/night (long sleep) in their own home in random counterbalanced order. Sleep was measured via wrist-worn actigraphs to confirm adherence to the sleep schedules (mean short sleep=5.9h, SD=0.3; mean long sleep=8.6h, SD=0.3, p<0.001). The Go/No-Go, BART, and Delay Discounting tasks were completed following both sleep conditions. Participants had more inhibition errors on the Go/No-Go task after short (mean false alarms=19.79%, SD=14.51) versus long sleep (mean=15.97%, SD=9.51, p=0.039). This effect was strongest in participants reporting longer habitual time in bed (p=0.04). There were no differences in performance following long- versus short-sleep for either delay discounting or the BART (p's>0.4). Overall, these results indicate that four days of PSD diminishes behavioral inhibition abilities, but may not alter impulsive decision-making. These findings contribute to the emerging understanding of how partial sleep deprivation, currently an epidemic, impacts cognitive ability. Future research should continue to explore the connection between PSD and cognitive functions, and ways to minimize the occurrence and negative consequences of short sleep.

Caffeine administration at night during extended wakefulness effectively mitigates performance impairment but not subjective assessments of fatigue and sleepiness

The current study investigated the effects of repeated caffeine administration on performance and subjective reports of sleepiness and fatigue during 50h extended wakefulness. Twenty-four, non-smokers aged 22.5±2.9y (mean±SD) remained awake for two nights (50h) in a controlled laboratory environment. During this period, 200mg of caffeine or placebo gum was administered at 01:00, 03:00, 05:00 and 07:00 on both nights (total of 800mg/night). Neurobehavioral performance and subjective reports were assessed throughout the wake period. Caffeine improved performance compared to placebo, but did not affect overall ratings of subjective sleepiness and fatigue. Performance and sleepiness worsened with increasing time awake for both conditions. However, caffeine slowed performance impairments such that after 50h of wakefulness performance was better following caffeine administration compared to placebo. Caffeine also slowed the increase in subjective sleepiness and performance ratings, but only during the first night of wakefulness. After two nights of sleep deprivation, there was no difference in sleepiness ratings between the two conditions. These results demonstrate that strategic administration of caffeine effectively mitigates performance impairments associated with 50h wakefulness but does not improve overall subjective assessments of sleepiness, fatigue and performance. Results indicate that while performance impairment is alleviated, individuals may continue to report feelings of sleepiness. Individuals who use caffeine as a countermeasure in sustained operations may feel as though caffeine is not effective despite impairments in objective performance being largely mitigated.

Development and Validation of the Cognition Test Battery for Spaceflight

BACKGROUND

Sustained high-level cognitive performance is of paramount importance for the success of space missions, which involve environmental, physiological, and psychological stressors that may affect brain functions. Despite subjective symptom reports of cognitive fluctuations in spaceflight, the nature of neurobehavioral functioning in space has not been clarified.

METHODS

We developed a computerized cognitive test battery (Cognition) that has sensitivity to multiple cognitive domains and was specifically designed for the high-performing astronaut population. Cognition consists of 15 unique forms of 10 neuropsychological tests that cover a range of cognitive domains, including emotion processing, spatial orientation, and risk decision making. Cognition is based on tests known to engage specific brain regions as evidenced by functional neuroimaging. Here we describe the first normative and acute total sleep deprivation data on the Cognition test battery as well as several efforts underway to establish the validity, sensitivity, feasibility, and acceptability of Cognition.

RESULTS

Practice effects and test-retest variability differed substantially between the 10 Cognition tests, illustrating the importance of normative data that both reflect practice effects and differences in stimulus set difficulty in the population of interest. After one night without sleep, medium to large effect sizes were observed for 3 of the 10 tests addressing vigilant attention (Cohen's d = 1.00), cognitive throughput (d = 0.68), and abstract reasoning (d = 0.65).

CONCLUSIONS

In addition to providing neuroimaging-based novel information on the effects of spaceflight on a range of cognitive functions, Cognition will facilitate comparing the effects of ground-based analogues to spaceflight, increase consistency across projects, and thus enable meta-analyses.

Legitimacy of concerns about caffeine and energy drink consumption

Whether caffeine and energy drink consumption presents a critical emerging health problem is not currently known. Available evidence suggests that energy drink consumption represents a change in the ways in which individuals in the United States consume caffeine but that the amount of caffeine consumed daily has not appreciably increased. In the present review, the question of whether Americans are sleep deprived (a potential reason for using caffeine) is briefly explored. Reported rates of daily caffeine consumption (based on beverage formulation) and data obtained from both civilian and military populations in the United States are examined, the efficacy of ingredients other than caffeine in energy drinks is discussed, and the safety and side effects of caffeine are addressed, including whether evidence supports the contention that excessive caffeine/energy drink consumption induces risky behavior. The available evidence suggests that the main legitimate concern regarding caffeine and energy drink use is the potential negative impact on sleep but that, otherwise, there is no cause for concern regarding caffeine use in the general population.

Gender differences in sleep deprivation effects on risk and inequality aversion: evidence from an economic experiment

Excessive working hours--even at night--are becoming increasingly common in our modern 24/7 society. The prefrontal cortex (PFC) is particularly vulnerable to the effects of sleep loss and, consequently, the specific behaviors subserved by the functional integrity of the PFC, such as risk-taking and pro-social behavior, may be affected significantly. This paper seeks to assess the effects of one night of sleep deprivation on subjects' risk and social preferences, which are probably the most explored behavioral domains in the tradition of Experimental Economics. This novel cross-over study employs thirty-two university students (gender-balanced) participating to 2 counterbalanced laboratory sessions in which they perform standard risk and social preference elicitation protocols. One session was after one night of undisturbed sleep at home, and the other was after one night of sleep deprivation in the laboratory. Sleep deprivation causes increased sleepiness and decreased alertness in all subjects. After sleep loss males make riskier decisions compared to the rested condition, while females do the opposite. Females likewise show decreased inequity aversion after sleep deprivation. As for the relationship between cognitive ability and economic decisions, sleep deprived individuals with higher cognitive reflection show lower risk aversion and more altruistic behavior. These results show that one night of sleep deprivation alters economic behavior in a gender-sensitive way. Females' reaction to sleep deprivation, characterized by reduced risky choices and increased egoism compared to males, may be related to intrinsic psychological gender differences, such as in the way men and women weigh up probabilities in their decision-making, and/or to the different neurofunctional substrate of their decision-making.

The effects of sleep restriction on executive inhibitory control and affect in young adults

PURPOSE

Young adults regularly experience restricted sleep due to a range of social, educational, and vocational commitments. Evidence suggests that extended periods of sleep deprivation negatively impact affective and inhibitory control mechanisms leading to behavioral consequences such as increased emotional reactivity and impulsive behavior. It is less clear whether acute periods of restricted sleep produce the same behavioral consequences.

METHODS

Nineteen young adults (m = 8 and f = 12) with habitual late bedtime (after 22:30 h) and wake time (after 06:30 h) completed a range of objective and subjective measures assessing sleepiness (psychomotor vigilance task and Karolinska sleepiness scale), inhibitory control (emotional go/no-go task and a balloon analog risk task), and affect (positive and negative affective schedule). Testing was counterbalanced across participants and occurred on two occasions once following restricted sleep and once following habitual sleep 1 week apart.

RESULTS

Compared with habitual sleep, sleep restriction produced significantly slower performance on the psychomotor vigilance task and higher subjective ratings of sleepiness on the Karolinska sleepiness scale. Sleep restriction also caused a significant decrease in positive affect but no change in negative affect on the affective schedule. Inhibitory control efficiency was significantly differentiated, with participants showing an increase in risk taking on the balloon analog risk task, but there was no evidence of increased reactivity to negative stimuli on the emotional go/no-go task.

CONCLUSIONS

Results suggest that even acute periods of sleep loss may cause deficits in affective experiences and increase impulsive and potentially high-risk behavior in young adults.

Sleep loss and risk-taking behavior: a review of the literature

Sleep loss is common problem with a wide range of consequences. One possible consequence of sleep loss may be risk-taking behavior (RTB). The present review examined the empirical literature on the relationship between sleep loss and RTB. We found 23 studies that met inclusion criteria. Overall, sleep loss was positively associated with RTB, and there was evidence that changes in sleep loss are causally related to changes in RTB. One possible mediator of the relationship between sleep loss and RTB was reduced functioning of the ventromedial prefrontal cortex (VMPFC). Possible moderators of this relationship included type of RTB measure and general versus specific RTB. We discussed limitations and recommendations for future research in this area.

Adenosine, caffeine, and performance: from cognitive neuroscience of sleep to sleep pharmacogenetics

An intricate interplay between circadian and sleep-wake homeostatic processes regulate cognitive performance on specific tasks, and individual differences in circadian preference and sleep pressure may contribute to individual differences in distinct neurocognitive functions. Attentional performance appears to be particularly sensitive to time of day modulations and the effects of sleep deprivation. Consistent with the notion that the neuromodulator, adenosine , plays an important role in regulating sleep pressure, pharmacologic and genetic data in animals and humans demonstrate that differences in adenosinergic tone affect sleepiness, arousal and vigilant attention in rested and sleep-deprived states. Caffeine--the most often consumed stimulant in the world--blocks adenosine receptors and normally attenuates the consequences of sleep deprivation on arousal, vigilance, and attention. Nevertheless, caffeine cannot substitute for sleep, and is virtually ineffective in mitigating the impact of severe sleep loss on higher-order cognitive functions. Thus, the available evidence suggests that adenosinergic mechanisms, in particular adenosine A2A receptor-mediated signal transduction, contribute to waking-induced impairments of attentional processes, whereas additional mechanisms must be involved in higher-order cognitive consequences of sleep deprivation. Future investigations should further clarify the exact types of cognitive processes affected by inappropriate sleep. This research will aid in the quest to better understand the role of different brain systems (e.g., adenosine and adenosine receptors) in regulating sleep, and sleep-related subjective state, and cognitive processes. Furthermore, it will provide more detail on the underlying mechanisms of the detrimental effects of extended wakefulness, as well as lead to the development of effective, evidence-based countermeasures against the health consequences of circadian misalignment and chronic sleep restriction.

Sleep deprivation alters effort discounting but not delay discounting of monetary rewards

STUDY OBJECTIVES

To determine whether sleep deprivation would affect the discounting of delayed rewards, of rewards entailing the expense of effort, or both.

DESIGN

We measured rates of two types of reward discounting under conditions of rested wakefulness (RW) and sleep deprivation (SD). Delay discounting was defined as the willingness to accept smaller monetary rewards sooner rather than larger monetary rewards later. Effort discounting was defined as the willingness to accept smaller rewards that require less effort to obtain (e.g., typing a small number of letter strings backward) over larger but more effortful rewards (e.g., typing more letter strings to receive the reward). The first two experiments used a crossover design in which one session was conducted after a normal night of sleep (RW), and the other after a night without sleep (SD). The first experiment evaluated only temporal discounting whereas the second evaluated temporal and effort discounting. In the second experiment, the discounting tasks were repeatedly administered prior to the state comparisons to minimize the effects of order and/or repeated testing. In a third experiment, participants were studied only once in a between-subject evaluation of discounting across states.

SETTING

The study took place in a research laboratory.

PARTICIPANTS

Seventy-seven healthy young adult participants: 20 in Experiment 1, 27 in Experiment 2, and 30 in Experiment 3.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Sleep deprivation elicited increased effort discounting but did not affect delay discounting.

CONCLUSIONS

The dissociable effects of sleep deprivation on two forms of discounting behavior suggest that they may have differing underlying neural mechanisms.

The effects of poor quality sleep on brain function and risk taking in adolescence

Insufficient sleep and poor quality sleep are pervasive during adolescence and relate to impairments in cognitive control and increased risk taking. However, the neurobiology underlying the association between sleep and adolescent behavior remains elusive. In the current study, we examine how poor sleep quality relates to cognitive control and reward related brain function during risk taking. Forty-six adolescents participated in a functional magnetic imaging (fMRI) scan during which they completed a cognitive control and risk taking task. Behaviorally, adolescents who reported poorer sleep also exhibited greater risk-taking. This association was paralleled by less recruitment of the dorsolateral prefrontal cortex (DLPFC) during cognitive control, greater insula activation during reward processing, and reduced functional coupling between the DLPFC and affective regions including the insula and ventral striatum during reward processing. Collectively, these results suggest that poor sleep may exaggerate the normative imbalance between affective and cognitive control systems, leading to greater risk-taking in adolescents.