Sleep deprivation amplifies reactivity of brain reward networks, biasing the appraisal of positive emotional experiences

Sleep mediates the link between resiliency and behavioural problems in children at high and low risk for alcoholism

Children of alcoholic parents are at greater risk for developing substance use problems. Having a parent with any mental illness increases the risk for sleep disorders in children. Using actigraphy, this study characterized sleep in children of alcoholics and community controls over a period of 1 week. This study further examined whether sleep characteristics of the children mediated the relationship between self-regulation indices (i.e. undercontrol and resiliency) and outcome measures of function (e.g. problem behaviours and perceived conflict at home). Eighty-two children (53 boys, 29 girls, 7.2-13.0 years old) were recruited from the ongoing Michigan Longitudinal Study. Seventeen participants had no parental history of alcohol abuse or dependence family history negative (FH-), 43 had at least one parent who was a recovered alcoholic, and 22 had at least one parent who met diagnostic criteria within the past 3 years. Sleep was assessed with actigraphy and sleep diaries for 1 week, and combined with secondary analysis of data collected for the longitudinal study. FH- children had more objectively measured total sleep time. More total sleep time was associated with greater resiliency and behavioural control, fewer teacher-reported behavioural problems, and less child-reported conflict at home. Further, total sleep time partially mediated the relationship between resiliency and perceived conflict, and between resiliency and externalizing problems. These findings suggest that in high-risk homes, the opportunity to obtain sufficient sleep is reduced, and that insufficient sleep further exacerbates the effects of impaired dispositional self-regulatory capacity on behavioural and emotional regulation.

Neural Reward Processing Mediates the Relationship between Insomnia Symptoms and Depression in Adolescence

STUDY OBJECTIVES

Emerging evidence suggests that insomnia may disrupt reward-related brain function-a potentially important factor in the development of depressive disorder. Adolescence may be a period during which such disruption is especially problematic given the rise in the incidence of insomnia and ongoing development of neural systems that support reward processing. The present study uses longitudinal data to test the hypothesis that disruption of neural reward processing is a mechanism by which insomnia symptoms-including nocturnal insomnia symptoms (NIS) and nonrestorative sleep (NRS)-contribute to depressive symptoms in adolescent girls.

METHOD

Participants were 123 adolescent girls and their caregivers from an ongoing longitudinal study of precursors to depression across adolescent development. NIS and NRS were assessed annually from ages 9 to 13 years. Girls completed a monetary reward task during a functional MRI scan at age 16 years. Depressive symptoms were assessed at ages 16 and 17 years. Multivariable regression tested the prospective associations between NIS and NRS, neural response during reward anticipation, and the mean number of depressive symptoms (omitting sleep problems).

RESULTS

NRS, but not NIS, during early adolescence was positively associated with late adolescent dorsal medial prefrontal cortex (dmPFC) response to reward anticipation and depressive symptoms. DMPFC response mediated the relationship between early adolescent NRS and late adolescent depressive symptoms.

CONCLUSIONS

These results suggest that NRS may contribute to depression by disrupting reward processing via altered activity in a region of prefrontal cortex involved in affective control. The results also support the mechanistic differentiation of NIS and NRS.

Decreased sleep duration is associated with increased fMRI responses to emotional faces in children

In adults and children, sleep loss is associated with affective dysregulation and increased responsivity to negative stimuli. Adult functional neuroimaging (fMRI) studies have demonstrated associations between restricted sleep and neural alterations in the amygdala and reward circuitry when viewing emotional picture and face stimuli. Despite this, few studies have examined the associations between short sleep duration and emotional responsivity in typically developing children, and no studies have investigated this relationship using fMRI. The current study examined the relationship between sleep duration and fMRI activation to emotional facial expressions in 15 male children (ages 7-11 years). During fMRI scanning, subjects viewed and made perceptual judgments regarding negative, neutral, and positive emotional faces. Maternal reported child sleep duration was negatively associated with (a) activation in the bilateral amygdala, left insula, and left temporal pole activation when viewing negative (i.e., fearful, disgust) vs. neutral faces, (b) right orbitofrontal and bilateral prefrontal activation when viewing disgust vs. neutral faces, and (c) bilateral orbitofrontal, right anterior cingulate, and left amygdala activation when viewing happy vs. neutral faces. Consistent with our prediction, we also noted that emotion-dependent functional connectivity between the bilateral amygdala and prefrontal cortex, cingulate, fusiform, and occipital cortex was positively associated with sleep duration. Paralleling similar studies in adults, these findings collectively suggest that decreased sleep duration in school-aged children may contribute to enhanced reactivity of brain regions involved in emotion and reward processing, as well as decreased emotion-dependent functional connectivity between the amygdala and brain regions associated with emotion regulation.

Sleep quality in healthy and mood-disordered persons predicts daily life emotional reactivity

Disordered sleep has been linked to impaired emotional functioning in healthy and depressed individuals. Little is known, however, about how chronic sleep problems influence emotional reactivity in everyday life. Participants with major or minor unipolar depressive disorder (n = 60) and healthy controls (n = 35) reported on sleep and emotional responses to daily life events using a computerised Experience Sampling Method. We examined whether impaired sleep quality influenced emotional reactivity to daily events, and if this relationship was altered by unipolar mood disorders. Among healthy individuals, sleep difficulties were associated with enhanced negative affect (NA) to unpleasant events and a dulled response to neutral events. However, among mood-disordered persons, sleep difficulties were associated with higher NA across all types of everyday life events. Impaired sleep quality differentially affects daily life emotional reactions as a function of depression.

Losing Neutrality: The Neural Basis of Impaired Emotional Control without Sleep

Sleep deprivation has been shown recently to alter emotional processing possibly associated with reduced frontal regulation. Such impairments can ultimately fail adaptive attempts to regulate emotional processing (also known as cognitive control of emotion), although this hypothesis has not been examined directly. Therefore, we explored the influence of sleep deprivation on the human brain using two different cognitive-emotional tasks, recorded using fMRI and EEG. Both tasks involved irrelevant emotional and neutral distractors presented during a competing cognitive challenge, thus creating a continuous demand for regulating emotional processing. Results reveal that, although participants showed enhanced limbic and electrophysiological reactions to emotional distractors regardless of their sleep state, they were specifically unable to ignore neutral distracting information after sleep deprivation. As a consequence, sleep deprivation resulted in similar processing of neutral and negative distractors, thus disabling accurate emotional discrimination. As expected, these findings were further associated with a decrease in prefrontal connectivity patterns in both EEG and fMRI signals, reflecting a profound decline in cognitive control of emotion. Notably, such a decline was associated with lower REM sleep amounts, supporting a role for REM sleep in overnight emotional processing. Altogether, our findings suggest that losing sleep alters emotional reactivity by lowering the threshold for emotional activation, leading to a maladaptive loss of emotional neutrality. Significance statement: Sleep loss is known as a robust modulator of emotional reactivity, leading to increased anxiety and stress elicited by seemingly minor triggers. In this work, we aimed to portray the neural basis of these emotional impairments and their possible association with frontal regulation of emotional processing, also known as cognitive control of emotion. Using specifically suited EEG and fMRI tasks, we were able to show that sleep deprivation alters emotional reactivity by triggering enhanced processing of stimuli regarded previously as neutral. These changes were further accompanied by diminished frontal connectivity, reduced REM sleep, and poorer performance. Therefore, we suggest that sleep loss alters emotional reactivity by lowering the threshold for emotional activation, leading to a maladaptive loss of emotional neutrality.

The brain functional connectome is robustly altered by lack of sleep

Sleep is a universal phenomenon necessary for maintaining homeostasis and function across a range of organs. Lack of sleep has severe health-related consequences affecting whole-body functioning, yet no other organ is as severely affected as the brain. The neurophysiological mechanisms underlying these deficits are poorly understood. Here, we characterize the dynamic changes in brain connectivity profiles inflicted by sleep deprivation and how they deviate from regular daily variability. To this end, we obtained functional magnetic resonance imaging data from 60 young, adult male participants, scanned in the morning and evening of the same day and again the following morning. 41 participants underwent total sleep deprivation before the third scan, whereas the remainder had another night of regular sleep. Sleep deprivation strongly altered the connectivity of several resting-state networks, including dorsal attention, default mode, and hippocampal networks. Multivariate classification based on connectivity profiles predicted deprivation state with high accuracy, corroborating the robustness of the findings on an individual level. Finally, correlation analysis suggested that morning-to-evening connectivity changes were reverted by sleep (control group)-a pattern which did not occur after deprivation. We conclude that both, a day of waking and a night of sleep deprivation dynamically alter the brain functional connectome.

Selective REM Sleep Deprivation Improves Expectation-Related Placebo Analgesia

The placebo effect is a neurobiological and psychophysiological process known to influence perceived pain relief. Optimization of placebo analgesia may contribute to the clinical efficacy and effectiveness of medication for acute and chronic pain management. We know that the placebo effect operates through two main mechanisms, expectations and learning, which is also influenced by sleep. Moreover, a recent study suggested that rapid eye movement (REM) sleep is associated with modulation of expectation-mediated placebo analgesia. We examined placebo analgesia following pharmacological REM sleep deprivation and we tested the hypothesis that relief expectations and placebo analgesia would be improved by experimental REM sleep deprivation in healthy volunteers. Following an adaptive night in a sleep laboratory, 26 healthy volunteers underwent classical experimental placebo analgesic conditioning in the evening combined with pharmacological REM sleep deprivation (clonidine: 13 volunteers or inert control pill: 13 volunteers). Medication was administered in a double-blind manner at bedtime, and placebo analgesia was tested in the morning. Results revealed that 1) placebo analgesia improved with REM sleep deprivation; 2) pain relief expectations did not differ between REM sleep deprivation and control groups; and 3) REM sleep moderated the relationship between pain relief expectations and placebo analgesia. These results support the putative role of REM sleep in modulating placebo analgesia. The mechanisms involved in these improvements in placebo analgesia and pain relief following selective REM sleep deprivation should be further investigated.

Impact of Impulse Control Disorders on Sleep-Wake Regulation in Parkinson's Disease

Sleep disturbances are common in patients with Parkinson's disease (PD) and are even more prevalent in patients with behavioural addictions, such as pathological gambling, compulsive sexual behaviour, compulsive buying, binge eating, punding, and the compulsive use of dopamine replacement therapy. An overview of the relationship between these impulse control disorders and sleep disturbances is given and potential underlying mechanisms and treatment strategies are covered.

Sleep deprivation affects reactivity to positive but not negative stimuli

OBJECTIVE

The current study examined the effects of partial and total sleep deprivation on emotional reactivity.

METHODS

Twenty-eight partially sleep-deprived participants and 31 totally sleep-deprived participants rated their valence and arousal responses to positive and negative pictures across four testing sessions during the day following partial sleep deprivation or during the night under total sleep deprivation.

RESULTS

The results suggest that valence and arousal ratings decreased under both sleep deprivation conditions. In addition, partial and total sleep deprivation had a greater negative effect on positive events than negative events.

CONCLUSION

These results suggest that sleep-deprived persons are more likely to respond less to positive events than negative events. One explanation for the current findings is that negative events could elicit more attentive behavior and thus stable responding under sleep deprivation conditions. As such, sleep deprivation could impact reactivity to emotional stimuli through automated attentional and self-regulatory processes.

Identification of Neurons with a Privileged Role in Sleep Homeostasis in Drosophila melanogaster

Sleep is thought to be controlled by two main processes: a circadian clock that primarily regulates sleep timing and a homeostatic mechanism that detects and responds to sleep need. Whereas abundant experimental evidence suggests that sleep need increases with time spent awake, the contributions of different brain arousal systems have not been assessed independently of each other to determine whether certain neural circuits, rather than waking per se, selectively contribute to sleep homeostasis. Using the fruit fly, Drosophila melanogaster, we found that sustained thermogenetic activation of three independent neurotransmitter systems promoted nighttime wakefulness. However, only sleep deprivation resulting from activation of cholinergic neurons was sufficient to elicit subsequent homeostatic recovery sleep, as assessed by multiple behavioral criteria. In contrast, sleep deprivation resulting from activation of octopaminergic neurons suppressed homeostatic recovery sleep, indicating that wakefulness can be dissociated from accrual of sleep need. Neurons that promote sleep homeostasis were found to innervate the central brain and motor control regions of the thoracic ganglion. Blocking activity of these neurons suppressed recovery sleep but did not alter baseline sleep, further differentiating between neural control of sleep homeostasis and daily fluctuations in the sleep/wake cycle. Importantly, selective activation of wake-promoting neurons without engaging the sleep homeostat impaired subsequent short-term memory, thus providing evidence that neural circuits that regulate sleep homeostasis are important for behavioral plasticity. Together, our data suggest a neural circuit model involving distinct populations of wake-promoting neurons, some of which are involved in homeostatic control of sleep and cognition.

Sleep deprivation alters choice strategy without altering uncertainty or loss aversion preferences

Sleep deprivation alters decision making; however, it is unclear what specific cognitive processes are modified to drive altered choices. In this manuscript, we examined how one night of total sleep deprivation (TSD) alters economic decision making. We specifically examined changes in uncertainty preferences dissociably from changes in the strategy with which participants engage with presented choice information. With high test-retest reliability, we show that TSD does not alter uncertainty preferences or loss aversion. Rather, TSD alters the information the participants rely upon to make their choices. Utilizing a choice strategy metric which contrasts the influence of maximizing and satisficing information on choice behavior, we find that TSD alters the relative reliance on maximizing information and satisficing information, in the gains domain. This alteration is the result of participants both decreasing their reliance on cognitively-complex maximizing information and a concomitant increase in the use of readily-available satisficing information. TSD did not result in a decrease in overall information use in either domain. These results show that sleep deprivation alters decision making by altering the informational strategies that participants employ, without altering their preferences.

Slow-wave disruption enhances the accessibility of positive memory traces

The purpose of this study was to explore the effects of slow-wave disruption on positive and negative word recognition in a sample of healthy control participants and those with major depressive disorder. Prior to sleep, participants learned a set of emotional and neutral words during an encoding task by responding whether or not the word described them. Following baseline sleep, participants underwent one night of selective slow-wave disruption by auditory stimuli. Accuracy and reaction time to a recognition word set, including both positive and negative words, was assessed in the morning. Repeated-measures ANOVA revealed a significant interaction between word valence and condition, with positive words recognized significantly faster than negative words after disruption, in only healthy control participants. There were no significant results in those with major depressive disorder, or with regard to accuracy. These results may add to the increasing body of literature suggesting a hedonic bias to positive stimuli following sleep disruption.

The implications of sleep disruption for cognitive and affective processing in methamphetamine abuse

Sleep is disrupted during active use of methamphetamine (MA), during withdrawal from the drug, and during abstinence from its use. However, relatively little is known about possible mediatory functions of disrupted sleep in the emergence, manifestation, and maintenance of cognitive and affective symptoms of MA abuse. We hypothesise that sleep functions as a mediator for stimulant drug effects. Specifically, we propose that objectively-measured sleep parameters can be used to explain some of the variability in the experience and presentation of memory deficits and emotion dysregulation in MA abusers. After describing how important healthy sleep is to unimpaired cognitive and affective functioning, we review literature describing how sleep is disrupted in MA abuse. Then, we provide a conceptual framework for our hypothesis by explaining the relationship between MA abuse, sleep disruption, memory deficits, emotion dysregulation, and changes in reward-related brain networks. We conclude by discussing implications of the hypothesis for research and treatment.

Metaphor and hyperassociativity: the imagination mechanisms behind emotion assimilation in sleep and dreaming

In this paper we propose an emotion assimilation function of sleep and dreaming. We offer explanations both for the mechanisms by which waking-life memories are initially selected for processing during sleep, and for the mechanisms by which those memories are subsequently transformed during sleep. We propose that emotions act as a marker for information to be selectively processed during sleep, including consolidation into long term memory structures and integration into pre-existing memory networks; that dreaming reflects these emotion assimilation processes; and that the associations between memory fragments activated during sleep give rise to measureable elements of dream metaphor and hyperassociativity. The latter are a direct reflection, and the phenomenological experience, of emotional memory assimilation processes occurring during sleep. While many theories previously have posited a role for emotion processing and/or emotional memory consolidation during sleep and dreaming, sleep theories often do not take enough account of important dream science data, yet dream research, when conducted systematically and under ideal conditions, can greatly enhance theorizing around the functions of sleep. Similarly, dream theories often fail to consider the implications of sleep-dependent memory research, which can augment our understanding of dream functioning. Here, we offer a synthesized view, taking detailed account of both sleep and dream data and theories. We draw on extensive literature from sleep and dream experiments and theories, including often-overlooked data from dream science which we believe reflects sleep phenomenology, to bring together important ideas and findings from both domains.

Sleep Deprivation Impairs the Human Central and Peripheral Nervous System Discrimination of Social Threat

Facial expressions represent one of the most salient cues in our environment. They communicate the affective state and intent of an individual and, if interpreted correctly, adaptively influence the behavior of others in return. Processing of such affective stimuli is known to require reciprocal signaling between central viscerosensory brain regions and peripheral-autonomic body systems, culminating in accurate emotion discrimination. Despite emerging links between sleep and affective regulation, the impact of sleep loss on the discrimination of complex social emotions within and between the CNS and PNS remains unknown. Here, we demonstrate in humans that sleep deprivation impairs both viscerosensory brain (anterior insula, anterior cingulate cortex, amygdala) and autonomic-cardiac discrimination of threatening from affiliative facial cues. Moreover, sleep deprivation significantly degrades the normally reciprocal associations between these central and peripheral emotion-signaling systems, most prominent at the level of cardiac-amygdala coupling. In addition, REM sleep physiology across the sleep-rested night significantly predicts the next-day success of emotional discrimination within this viscerosensory network across individuals, suggesting a role for REM sleep in affective brain recalibration. Together, these findings establish that sleep deprivation compromises the faithful signaling of, and the "embodied" reciprocity between, viscerosensory brain and peripheral autonomic body processing of complex social signals. Such impairments hold ecological relevance in professional contexts in which the need for accurate interpretation of social cues is paramount yet insufficient sleep is pervasive.

Sleep disturbances, TBI and PTSD: Implications for treatment and recovery

Post-Traumatic Stress Disorder (PTSD), traumatic brain injury (TBI), and sleep problems significantly affect recovery and functional status in military personnel and Veterans returning from combat. Despite recent attention, sleep is understudied in the Veteran population. Few treatments and rehabilitation protocols target sleep, although poor sleep remains at clinical levels and continues to adversely impact functioning even after the resolution of PTSD or mild TBI symptoms. Recent developments in non-pharmacologic sleep treatments have proven efficacious as stand-alone interventions and have potential to improve treatment outcomes by augmenting traditional behavioral and cognitive therapies. This review discusses the extensive scope of work in the area of sleep as it relates to TBI and PTSD, including pathophysiology and neurobiology of sleep; existing and emerging treatment options; as well as methodological issues in sleep measurements for TBI and PTSD. Understanding sleep problems and their role in the development and maintenance of PTSD and TBI symptoms may lead to improvement in overall treatment outcomes while offering a non-stigmatizing entry in mental health services and make current treatments more comprehensive by helping to address a broader spectrum of difficulties.

Sleep and circadian contributions to adolescent alcohol use disorder

Adolescence is a time of marked changes across sleep, circadian rhythms, brain function, and alcohol use. Starting at puberty, adolescents' endogenous circadian rhythms and preferred sleep times shift later, often leading to a mismatch with the schedules imposed by secondary education. This mismatch induces circadian misalignment and sleep loss, which have been associated with affect dysregulation, increased drug and alcohol use, and other risk-taking behaviors in adolescents and adults. In parallel to developmental changes in sleep, adolescent brains are undergoing structural and functional changes in the circuits subserving the pursuit and processing of rewards. These developmental changes in reward processing likely contribute to the initiation of alcohol use during adolescence. Abundant evidence indicates that sleep and circadian rhythms modulate reward function, suggesting that adolescent sleep and circadian disturbance may contribute to altered reward function, and in turn, alcohol involvement. In this review, we summarize the relevant evidence and propose that these parallel developmental changes in sleep, circadian rhythms, and neural processing of reward interact to increase risk for alcohol use disorder (AUD).

Sleep and food intake: A multisystem review of mechanisms in children and adults

The foods we eat have substantial impact on our health, and excessive food intake is associated with numerous long-term health conditions. It is therefore essential to understand the factors influencing this crucial health behavior. Research has identified sleep problems as one such factor; however, little research has examined how sleep problems impact food intake. Using a multisystemic perspective, this article proposes a variety of ways in which sleep problems likely increase food intake and illustrates the need for research to empirically examine these underlying mechanisms. Such research would have important treatment implications for health conditions often treated with dietary interventions.

Rapid-Eye-Movement-Sleep (REM) Associated Enhancement of Working Memory Performance after a Daytime Nap

The main objective was to study the impact of a daytime sleep opportunity on working memory and the mechanism behind such impact. This study adopted an experimental design in a sleep research laboratory. Eighty healthy college students (Age:17-23, 36 males) were randomized to either have a polysomnography-monitored daytime sleep opportunity (Nap-group, n=40) or stay awake (Wake-group, n=40) between the two assessment sessions. All participants completed a sleep diary and wore an actigraph-watch for 5 days before and one day after the assessment sessions. They completed the state-measurement of sleepiness and affect, in addition to a psychomotor vigilance test and a working memory task before and after the nap/wake sessions. The two groups did not differ in their sleep characteristics prior to and after the lab visit. The Nap-group had higher accuracy on the working memory task, fewer lapses on the psychomotor vigilance test and lower state-sleepiness than the Wake-group. Within the Nap-group, working memory accuracy was positively correlated with duration of rapid eye movement sleep (REM) and total sleep time during the nap. Our findings suggested that "sleep gain" during a daytime sleep opportunity had significant positive impact on working memory performance, without affecting subsequent nighttime sleep in young adult, and such impact was associated with the duration of REM. While REM abnormality has long been noted in pathological conditions (e.g. depression), which are also presented with cognitive dysfunctions (e.g. working memory deficits), this was the first evidence showing working memory enhancement associated with REM in daytime napping in college students, who likely had habitual short sleep duration but were otherwise generally healthy.

Effects of sleep on memory for conditioned fear and fear extinction

Learning and memory for extinction of conditioned fear is a basic mammalian mechanism for regulating negative emotion. Sleep promotes both the consolidation of memory and the regulation of emotion. Sleep can influence consolidation and modification of memories associated with both fear and its extinction. After brief overviews of the behavior and neural circuitry associated with fear conditioning, extinction learning, and extinction memory in the rodent and human, interactions of sleep with these processes will be examined. Animal and human studies suggest that sleep can serve to consolidate both fear and extinction memory. In humans, sleep also promotes generalization of extinction memory. Time-of-day effects on extinction learning and generalization are also seen. Rapid eye movement (REM) may be a sleep stage of particular importance for the consolidation of both fear and extinction memory as evidenced by selective REM deprivation experiments. REM sleep is accompanied by selective activation of the same limbic structures implicated in the learning and memory of fear and extinction. Preliminary evidence also suggests extinction learning can take place during slow wave sleep. Study of low-level processes such as conditioning, extinction, and habituation may allow sleep effects on emotional memory to be identified and inform study of sleep's effects on more complex, emotionally salient declarative memories. Anxiety disorders are marked by impairments of both sleep and extinction memory. Improving sleep quality may ameliorate anxiety disorders by strengthening naturally acquired extinction. Strategically timed sleep may be used to enhance treatment of anxiety by strengthening therapeutic extinction learned via exposure therapy. (PsycINFO Database Record

Frequency-dependent changes of local resting oscillations in sleep-deprived brain

Sleep deprivation (SD) adversely affects brain function and is accompanied by frequency dependent changes in EEG. Recent studies have suggested that BOLD fluctuations pertain to a spatiotemporal organization with different frequencies. The present study aimed to investigate the frequency-dependent SD-related brain oscillatory activity by using the amplitude of low-frequency fluctuation (ALFF) analysis. The ALFF changes were measured across different frequencies (Slow-4: 0.027–0.073 Hz; Slow-5: 0.01–0.027 Hz; and Typical band: 0.01–0.08 Hz) in 24 h SD as compared to rested wakeful during resting-state fMRI. Sixteen volunteers underwent two fMRI sessions, once during rested wakefulness and once after 24 h of SD. SD showed prominently decreased ALFF in the right inferior parietal lobule (IPL), bilateral orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC), while increased ALFF in the visual cortex, left sensorimotor cortex and fusiform gyrus. Across the Slow-4 and Slow-5, results differed significantly in the OFC, DLPFC, thalamus and caudate in comparison to typical frequency band; and Slow-4 showed greater differences. In addition, negative correlations of behavior performance and ALFF patterns were found mainly in the right IPL across the typical frequency band. These observations provided novel insights about the physiological responses of SD, identified how it disturbs the brain rhythms, and linked SD with frequency-dependent alterations in amplitude patterns.

Altered salience network connectivity predicts macronutrient intake after sleep deprivation

Although insufficient sleep is a well-recognized risk factor for overeating and weight gain, the neural mechanisms underlying increased caloric (particularly fat) intake after sleep deprivation remain unclear. Here we used resting-state functional magnetic resonance imaging and examined brain connectivity changes associated with macronutrient intake after one night of total sleep deprivation (TSD). Compared to the day following baseline sleep, healthy adults consumed a greater percentage of calories from fat and a lower percentage of calories from carbohydrates during the day following TSD. Subjects also exhibited increased brain connectivity in the salience network from the dorsal anterior cingulate cortex (dACC) to bilateral putamen and bilateral anterior insula (aINS) after TSD. Moreover, dACC-putamen and dACC-aINS connectivity correlated with increased fat and decreased carbohydrate intake during the day following TSD, but not during the day following baseline sleep. These findings provide a potential neural mechanism by which sleep loss leads to increased fat intake.

How acute total sleep loss affects the attending brain: a meta-analysis of neuroimaging studies

STUDY OBJECTIVES

Attention is a cognitive domain that can be severely affected by sleep deprivation. Previous neuroimaging studies have used different attention paradigms and reported both increased and reduced brain activation after sleep deprivation. However, due to large variability in sleep deprivation protocols, task paradigms, experimental designs, characteristics of subject populations, and imaging techniques, there is no consensus regarding the effects of sleep loss on the attending brain. The aim of this meta-analysis was to identify brain activations that are commonly altered by acute total sleep deprivation across different attention tasks.

DESIGN

Coordinate-based meta-analysis of neuroimaging studies of performance on attention tasks during experimental sleep deprivation.

METHODS

The current version of the activation likelihood estimation (ALE) approach was used for meta-analysis. The authors searched published articles and identified 11 sleep deprivation neuroimaging studies using different attention tasks with a total of 185 participants, equaling 81 foci for ALE analysis.

RESULTS

The meta-analysis revealed significantly reduced brain activation in multiple regions following sleep deprivation compared to rested wakefulness, including bilateral intraparietal sulcus, bilateral insula, right prefrontal cortex, medial frontal cortex, and right parahippocampal gyrus. Increased activation was found only in bilateral thalamus after sleep deprivation compared to rested wakefulness.

CONCLUSION

Acute total sleep deprivation decreases brain activation in the fronto-parietal attention network (prefrontal cortex and intraparietal sulcus) and in the salience network (insula and medial frontal cortex). Increased thalamic activation after sleep deprivation may reflect a complex interaction between the de-arousing effects of sleep loss and the arousing effects of task performance on thalamic activity.

REM sleep and memory reorganization: Potential relevance for psychiatry and psychotherapy

Sleep can foster the reorganization of memory, i.e. the emergence of new memory content that has not directly been encoded. Current neurophysiological and behavioral evidence can be integrated into a model positing that REM sleep particularly promotes the disintegration of existing schemas and their recombination in the form of associative thinking, creativity and the shaping of emotional memory. Particularly, REM sleep related dreaming might represent a mentation correlate for the reconfiguration of memory. In a final section, the potential relevance for psychiatry and psychotherapy is discussed.

Sleep and emotional functions

In this chapter, we review studies investigating the role of sleep in emotional functions. In particular, evidence has recently accumulated to show that brain regions involved in the processing of emotional and reward-related information are activated during sleep. We suggest that such activation of emotional and reward systems during sleep underlies the reprocessing and consolidation of memories with a high affective and motivational relevance for the organism. We also propose that these mechanisms occurring during sleep promote adapted cognitive and emotional responses in the waking state, including overnight performance improvement, creativity, and sexual functions. Activation across emotional-limbic circuits during sleep also appears to promote emotional maturation and the emergence of consciousness in the developing brain.

Suicidal ideation in depressed postpartum women: Associations with childhood trauma, sleep disturbance and anxiety

BACKGROUND

Suicide is one of the leading causes of death in postpartum women. Identifying modifiable factors related to suicide risk in mothers after delivery is a public health priority. Our study aim was to examine associations between suicidal ideation (SI) and plausible risk factors (experience of abuse in childhood or as an adult, sleep disturbance, and anxiety symptoms) in depressed postpartum women.

METHODS

This secondary analysis included 628 depressed mothers at 4-6 weeks postpartum. Diagnosis was confirmed with the Structured Clinical Interview for DSM-IV. We examined SI from responses to the Edinburgh Postnatal Depression Scale-EPDS item 10; depression levels on the Structured Interview Guide for the Hamilton Depression Rating Scale, Atypical Depression Symptoms (SIGH-ADS); plus sleep disturbance and anxiety levels with subscales from the EPDS and SIGH-ADS items on sleep and anxiety symptoms.

RESULTS

Of the depressed mothers, 496 (79%) 'never' had thoughts of self-harm; 98 (15.6%) 'hardly ever'; and 34 (5.4%) 'sometimes' or 'quite often'. Logistic regression models indicated that having frequent thoughts of self-harm was related to childhood physical abuse (odds ratio-OR = 1.68, 95% CI = 1.00, 2.81); in mothers without childhood physical abuse, having frequent self-harm thoughts was related to sleep disturbance (OR = 1.15, 95% CI = 1.02, 1.29) and anxiety symptoms (OR = 1.11, 95% CI = 1.01, 1.23).

DISCUSSION

Because women with postpartum depression can present with frequent thoughts of self-harm and a high level of clinical complexity, conducting a detailed safety assessment, that includes evaluation of childhood abuse history and current symptoms of sleep disturbance and anxiety, is a key component in the management of depressed mothers.

Current and future directions in clinical fatigue management: An update for emergency medicine practitioners

Physicians worldwide are working round the clock to meet the demands of healthcare systems, especially in acute medical settings such as EDs. Demanding shift work schedules cause fatigue and thus deterioration in mood and motor performance. This article explores the effects of sleep deprivation, focusing on cognition, executive decision-making and the implications for clinical care. Humans are capable of functioning and even adapting to sleep restriction; however, clinicians should be aware of pitfalls and absolute minimums for sleep. Fatigue management training shows promise in enhancing safety in aviation and might have a role in medical shift work. Strategic napping improves performance during night shift in the ED, but does not fully negate fatigue. Drugs offer limited benefit for performance under sleep-deprived conditions, and whenever possible, sleep and/or strategic napping takes precedence.

Module number of default mode network: inter-subject variability and effects of sleep deprivation

Sleep deprivation have shown its great influence on the default mode network (DMN). The DMN is a core system in resting state brain activity. Recent studies have focused on its subsystems and multiple functions. However, the individual specific organization of the DMN is rarely investigated. As the effects of sleep deprivation (SD) on mood are well documented, a more interesting question is whether changes in the processing of emotional information due to sleep deprivation are related to any specific topological properties of the DMN. In this study, we proposed an index, module number of DMN (mnDMN), to measure the specific modular structure of the DMN for each individual. Our results showed that the DMN was generally split into two modules after SD, and the decreased functional connectivity between the two modules was related to a worsening of the participants׳ self-reported emotional state. Furthermore, the mnDMN was correlated with participants' rating scores of high valence pictures in the SD session, indicating that the mnDMN might reflect mood valuation in the human brain. Overall, our research reveals the diversity of the DMN, and may contribute towards a better understanding of the properties and functions of the DMN.

Altered resting-state amygdala functional connectivity after 36 hours of total sleep deprivation

Objectives

Recent neuroimaging studies have identified a potentially critical role of the amygdala in disrupted emotion neurocircuitry in individuals after total sleep deprivation (TSD). However, connectivity between the amygdala and cerebral cortex due to TSD remains to be elucidated. In this study, we used resting-state functional MRI (fMRI) to investigate the functional connectivity changes of the basolateral amygdala (BLA) and centromedial amygdala (CMA) in the brain after 36 h of TSD.

Materials and Methods

Fourteen healthy adult men aged 25.9±2.3 years (range, 18–28 years) were enrolled in a within-subject crossover study. Using the BLA and CMA as separate seed regions, we examined resting-state functional connectivity with fMRI during rested wakefulness (RW) and after 36 h of TSD.

Results

TSD resulted in a significant decrease in the functional connectivity between the BLA and several executive control regions (left dorsolateral prefrontal cortex [DLPFC], right dorsal anterior cingulate cortex [ACC], right inferior frontal gyrus [IFG]). Increased functional connectivity was found between the BLA and areas including the left posterior cingulate cortex/precuneus (PCC/PrCu) and right parahippocampal gyrus. With regard to CMA, increased functional connectivity was observed with the rostral anterior cingulate cortex (rACC) and right precentral gyrus.

Conclusion

These findings demonstrate that disturbance in amygdala related circuits may contribute to TSD psychophysiology and suggest that functional connectivity studies of the amygdala during the resting state may be used to discern aberrant patterns of coupling within these circuits after TSD.

Circadian rhythms and risk for substance use disorders in adolescence

PURPOSE OF REVIEW

This article explores recent research in adolescent circadian rhythms, neurobiological changes influencing affective regulation and reward responding, and the emergence of substance use and related problems.

RECENT FINDINGS

Recent findings have confirmed that adolescents with drug and alcohol problems are also beset by sleep problems, and have advanced our understanding of the relationship between sleep problems and substance involvement in this developmental period. During adolescence, a shift to later preferred sleep times interacts with early school start times to cause sleep loss and circadian misalignment. Sleep loss and circadian misalignment may disrupt reward-related brain function and impair inhibitory control. Deficits or delays in mature reward and inhibitory functions may contribute to adolescent alcohol use and other substance involvement.

SUMMARY

An integration of the available research literature suggests that changes in sleep and circadian rhythms during adolescence may contribute to accelerated substance use and related problems.

The interplay between sleep and emotion regulation: conceptual framework empirical evidence and future directions

Emotions are biologically-based responses that help an organism meet challenges and opportunities, and involve changes in subjective experience, behavior, and physiology. Emotions arise when something important to us is at stake. Although many factors have been associated with healthy emotional regulation, the role of sleep in this process has been largely ignored. Recent studies, however, have begun to delineate how sleep critically affects emotional functioning. Nighttime sleep affects daytime mood, emotional reactivity and the capacity to regulate positive and negative emotions; conversely, daytime experiences affect sleep. Hence, there is a complex interplay between sleep and emotional regulation. The objective of this article is to examine this interplay in adults. This objective is addressed by utilizing a framework that identifies key aspects of the relationship between sleep and emotion. We propose that the connectivity between the emotional centers of the brain--the prefontal cortex and the amygdala--is in part dependent on the homeostatic sleep system such that connectivity between these brain networks is higher when rested and lower when sleep deprived. High connectivity drives more efficient executive functioning, while a disconnect leads to poor executive functioning capacity including emotional reactivity and impulsivity. The cognitive effects of the homeostatic system are couple with the mood regulation effects of the circadian system together dictating the degree to which one experiences emotional regulation or dysregulation. Further, the affective brain systems of individuals with clinical symptomology and/or pathology are suggested to be more vulnerable to homeostatic pressure and circadian lows or misalignment resulting in increased affective clinical symptomology. We review empirical evidence that supports this framework and explore the implications of this framework. Finally, we describe future directions for this type of work.

Sleepiness induced by sleep-debt enhanced amygdala activity for subliminal signals of fear

Background

Emotional information is frequently processed below the level of consciousness, where subcortical regions of the brain are thought to play an important role. In the absence of conscious visual experience, patients with visual cortex damage discriminate the valence of emotional expression. Even in healthy individuals, a subliminal mechanism can be utilized to compensate for a functional decline in visual cognition of various causes such as strong sleepiness. In this study, sleep deprivation was simulated in healthy individuals to investigate functional alterations in the subliminal processing of emotional information caused by reduced conscious visual cognition and attention due to an increase in subjective sleepiness. Fourteen healthy adult men participated in a within-subject crossover study consisting of a 5-day session of sleep debt (SD, 4-h sleep) and a 5-day session of sleep control (SC, 8-h sleep). On the last day of each session, participants performed an emotional face-viewing task that included backward masking of nonconscious presentations during magnetic resonance scanning.

Results

Finally, data from eleven participants who were unaware of nonconscious face presentations were analyzed. In fear contrasts, subjective sleepiness was significantly positively correlated with activity in the amygdala, ventromedial prefrontal cortex, hippocampus, and insular cortex, and was significantly negatively correlated with the secondary and tertiary visual areas and the fusiform face area. In fear-neutral contrasts, subjective sleepiness was significantly positively correlated with activity of the bilateral amygdala. Further, changes in subjective sleepiness (the difference between the SC and SD sessions) were correlated with both changes in amygdala activity and functional connectivity between the amygdala and superior colliculus in response to subliminal fearful faces.

Conclusion

Sleepiness induced functional decline in the brain areas involved in conscious visual cognition of facial expressions, but also enhanced subliminal emotional processing via superior colliculus as represented by activity in the amygdala. These findings suggest that an evolutionally old and auxiliary subliminal hazard perception system is activated as a compensatory mechanism when conscious visual cognition is impaired. In addition, enhancement of subliminal emotional processing might cause involuntary emotional instability during sleep debt through changes in emotional response to or emotional evaluation of external stimuli.

[Placebo analgesia and sleep]

The placebo response is a psychobiological phenomenon for clinical benefits following the administration of an inert substance whatever its form. This phenomenon can be attributed to a wide range of neurobiological processes, such as expectations of relief, the Pavlovian conditioning and learning, emotional regulation, and reward mechanisms, which are themselves under the influence of processes that take place during sleep. The study of placebo analgesia in healthy from a placebo conditioning associated with analgesic suggestions has highlighted a relationship between sleep, expectations of relief and placebo analgesia: when the induction is persuasive before sleep, expectations of relief modulate placebo response the next morning and paradoxical sleep correlates negatively with both expectations and the placebo response. When the analgesic experience before sleep is less persuasive, expectations of relief are still present but no longer interact with placebo analgesia while paradoxical sleep no longer correlates with the analgesic placebo response. Sleep-processes especially during paradoxical sleep seem to influence the relationship between expectations of relief and placebo analgesia. In this review, we describe the relationship between sleep and placebo analgesia, the mechanisms involved in the placebo response (e.g., conditioning, learning, memory, reward) and their potential link with sleep that could make it a special time for the building placebo response.

Differential neural responses to child and sexual stimuli in human fathers and non-fathers and their hormonal correlates

Despite the well-documented importance of paternal caregiving for positive child development, little is known about the neural changes that accompany the transition to fatherhood in humans, or about how changes in hormone levels affect paternal brain function. We compared fathers of children aged 1-2 with non-fathers in terms of hormone levels (oxytocin and testosterone), neural responses to child picture stimuli, and neural responses to visual sexual stimuli. Compared to non-fathers, fathers had significantly higher levels of plasma oxytocin and lower levels of plasma testosterone. In response to child picture stimuli, fathers showed stronger activation than non-fathers within regions important for face emotion processing (caudal middle frontal gyrus [MFG]), mentalizing (temporo-parietal junction [TPJ]) and reward processing (medial orbitofrontal cortex [mOFC]). On the other hand, non-fathers had significantly stronger neural responses to sexually provocative images in regions important for reward and approach-related motivation (dorsal caudate and nucleus accumbens). Testosterone levels were negatively correlated with responses to child stimuli in the MFG. Surprisingly, neither testosterone nor oxytocin levels predicted neural responses to sexual stimuli. Our results suggest that the decline in testosterone that accompanies the transition to fatherhood may be important for augmenting empathy toward children.

Effects of sleep loss on emotion recognition: a dissociation between face and word stimuli

Short-term sleep deprivation, or extended wakefulness, adversely affects cognitive functions and behavior. However, scarce research has addressed the effects of sleep deprivation (SD) on emotional processing. In this study, we investigated the impact of reduced vigilance due to moderate sleep deprivation on the ability to recognize emotional expressions of faces and emotional content of words. Participants remained awake for 24 h and performed the tasks in two sessions, one in which they were not affected by sleep loss (baseline; BSL), and other affected by SD, according to a counterbalanced sequence. Tasks were carried out twice at 10:00 and 4:00 am, or at 12:00 and 6:00 am. In both tasks, participants had to respond to the emotional valence of the target stimulus: negative, positive, or neutral. The results showed that in the word task, sleep deprivation impaired recognition irrespective of the emotional valence of words. However, sleep deprivation impaired recognition of emotional face expressions mainly when they showed a neutral expression. Emotional face expressions were less affected by the sleep loss, but positive faces were more resistant than negative faces to the detrimental effect of sleep deprivation. The differential effects of sleep deprivation on recognition of the different emotional stimuli are indicative of emotional facial expressions being stronger emotional stimuli than emotional laden words. This dissociation may be attributed to the more automatic sensory encoding of emotional facial content.

An increase in the cerebral infarction area during fatigue is mediated by il-6 through an induction of fibrinogen synthesis

OBJECTIVES

Our study aimed to investigate the impact of fatigue on the severity of stroke and to explore the underlying mechanisms.

METHODS

Fatigued male rats underwent middle cerebral artery occlusion and the infarcted brain area was determined. Then, coagulation parameters were assessed in the fatigued group and a control group. In addition, the level of fibrinogen was determined in rats deprived of sleep for various numbers of days. To study whether interleukin-6 was involved in fibrinogen synthesis during fatigue, we also measured levels of interleukin-6 in rats deprived of sleep for various numbers of days. Furthermore, brain injury by middle cerebral artery occlusion was measured in wild-type mice, interleukin-6-/- mice and wild-type mice treated with bezafibrate.

RESULTS

More severe cerebral infarction was observed in the fatigued rats, resulting in an infarct ratio of 23.4%. The infarct ratio was significantly increased in the fatigued rats compared with that in the control group (8%, p<0.05). The level of fibrinogen was increased significantly in the fatigued rats compared with that in the control group. In addition, a marked reduction in fibrinogen level was observed in the fatigued interleukin-6-/- mice compared to their wild-type counterparts, whereas no difference was observed between fatigued wild-type mice and interleukin-6-/- rats treated with recombinant human interleukin-6. The reduction in brain injury due to middle cerebral artery occlusion during fatigue was observed in interleukin-6-/- mice and wild-type mice treated with bezafibrate.

CONCLUSION

Fatigue could increase stroke severity and was associated with the interleukin-6-induced expression of fibrinogen.