Recovery from Unrecognized Sleep Loss Accumulated in Daily Life Improved Mood Regulation via Prefrontal Suppression of Amygdala Activity

The dynamic responses of mood and sleep physiology to chronic sleep restriction and subsequent recovery sleep

Healthy sleep of sufficient duration preserves mood and disturbed sleep is a risk factor for a range of psychiatric disorders. As adults commonly experience chronic sleep restriction (SR), an enhanced understanding of the dynamic relationship between sleep and mood is needed, including whether susceptibility to SR-induced mood disturbance differs between sexes. To address these gaps, data from N = 221 healthy adults who completed one of the two multi-day laboratory studies with identical 9-day SR protocols were analyzed. Participants randomized to the SR (n = 205) condition underwent 5 nights of SR to 4 hours of time-in-bed and were then randomized to one of the seven sleep doses that ranged from 0 to 12 hours in 2 hours increments; participants randomized to the control (n = 16) condition received 10 hours time-in-bed on all study nights. The Profile of Mood States (POMS) was used to assess mood every 2 hours during wakefulness and markers of sleep homeostasis (EEG slow-wave activity (SWA)) were derived via polysomnography. Mood progressively deteriorated across SR with marked disturbances in somatic mood components. Altered sleep physiology contributed to mood disturbance whereby increased EEG SWA was associated with increased POMS Total Mood Disturbance scores, a finding specific to males. The mood was restored in a dose-response fashion where improvements were greater with longer sleep doses. These findings suggest that when lifestyle and environmental factors are inhibited in the laboratory, the affective consequences of chronic sleep loss are primarily somatic mood disturbances. Altered sleep homeostasis may contribute to mood disturbance, yet sleep-dependent mechanisms may be sex-specific.

Associations Between Multiple Dimensions of Sleep and Mood During Early Adolescence: A Longitudinal Daily Diary Study

Prior research has observed reciprocal associations between sleep and mood. However, these findings are primarily based on the examination of one or two aspects of sleep behaviors (e.g., duration, quality), neglecting how multiple dimensions of sleep (particularly indicators pertinent to adolescence, e.g., sleep variability) are linked to adolescent mood both daily and longitudinally. Drawing on a multidimensional framework for sleep, this study addressed the knowledge gap by examining the directionality of and differential effects for associations between multiple dimensions of sleep and mood during early adolescence. Participants were 273 Chinese early adolescents (34.39% girls; Mage = 11.57, SD = 1.31), who filled out a pre-survey on demographics (T1) and 7-day diaries on sleep (i.e., duration, quality, disturbance, and latency) and mood (i.e., positive and negative mood). Adolescents completed another wave of diary reports 1 year later (T2). Findings revealed both bidirectional and unidirectional, within-person effects depending on specific sleep parameters, suggesting differential associations between multiple dimensions of sleep and mood. Specifically, on days when adolescents had longer sleep latency and greater disturbance than usual, they reported higher negative mood the next day, whereas higher negative mood was linked to poorer sleep quality the next day. The longitudinal investigation found that greater variability in sleep quality at T1 was associated with higher negative mood at T2. These findings underscore the importance of understanding the complex interplay between sleep and mood by examining the directionality of and differential effects for the daily and longer-term associations between multiple dimensions of sleep and mood among early adolescents.

Effects of replacing sedentary time with alterations in physical activity or sleep on mood states in Chinese young adults during the pandemic

BACKGROUND

Poor mood states pose the most frequent mental health, creating a considerable burden to global public health. Sedentary behavior is an essential factor affecting mood states, however, previous measures to reduce sedentary time in Chinese young adults have focused only on increasing physical activity (PA). Sedentary, PA, and sleep make up a person's day from the standpoint of time use. It is not known whether reallocating sedentary time to different types of PA (e.g. daily PA and structured PA) or sleep during an epidemic has an effect on mood states. Therefore, this study aimed to examine the association between replacing sedentary time with different types of PA or sleep during the pandemic and the mood states of Chinese young adults and to further examine whether this association varies across sleep populations and units of replacement time.

METHOD

3,579 young adults aged 18 to 25 years living in China and self-isolating at home during the COVID-19 outbreak were invited to complete an online questionnaire between February from 23 to 29, 2020. Subjects' PA, sedentary time, and mood states were assessed using the International Physical Activity Questionnaire and the Chinese version of the Profile of Mood States, respectively. Participants also reported sleep duration and some sociodemographic characteristics. Participants were divided into short sleepers (< 7 h/d), normal sleepers (7-9 h/d), and long sleepers (> 9 h/d) based upon their reported sleep duration. Relevant data were analyzed using Pearson correlation analysis and isotemporal substitution model (ISM).

RESULTS

Sedentary time was negatively associated with mood states in Chinese young adults during the pandemic (r = 0.140) and correlated strongest among short sleepers (r = 0.203). Substitution of sedentary time with structured PA was associated with good mood states (β=-0.28, 95% CI: -0.49, -0.08). Additionally, substituting sedentary time with daily PA (e.g. occupational PA, household PA) was also associated with good mood states among normal sleepers (β=-0.24, 95% CI: -0.46, -0.02). The substitution of sedentary time with sleep could bring mood benefits (β=-0.35, 95% CI: -0.47, -0.23). This benefit was particularly prominent among short sleepers. Furthermore, for long sleepers, replacing sedentary time with sleep time also resulted in significant mood benefits (β=-0.41, 95% CI: -0.69, -0.12). The longer the duration of replacing sedentary behavior with different types of PA or sleep, the greater the mood benefits.

CONCLUSIONS

A reallocation of as little as 10 min/day of sedentary time to different types of PA or sleep is beneficial for the mood states of young adults. The longer the reallocation, the greater the benefit. Our results demonstrate a feasible and practical behavior alternative for improving mood states of Chinese young adults.

Examining bi-directional links between loneliness, social connectedness and sleep from a trait and state perspective

Greater loneliness as well as a lack of social connectedness have often been associated with poorer sleep. However, the temporal dynamics and direction of these associations remain unclear. Aim of the current study was to examine bi-directional associations between loneliness/social connectedness and sleep in 48 stress-exposed medical students during their first medical internship, considered a period of heightened stress. We obtained trait-level questionnaire data on loneliness and global sleep completed before and during the internship as well as state-level diary- and wearable-based data on daily changes in social connectedness and sleep collected twice over the period of seven consecutive days, once before and once during the internship. Bi-directional associations among greater loneliness and higher daytime dysfunction on trait-level were identified. In addition, several uni-directional associations between loneliness/social connectedness and sleep were found on trait- and state-level. In sum, findings of this study point at a bi-directional relation among loneliness/social connectedness and sleep, in which variables seem to reciprocally influence each other across longer-term periods as well as on a day-to-day basis.

The influence of infant sleep problems and sleep training on maternal subjective well-being

Background

Disturbed sleep during infancy and early childhood can have a detrimental effect on parental sleep and consequently parental well-being. However, there is a paucity of research on how perceived child sleep problems and behavioural sleep interventions as treatment influence maternal subjective well-being.

Aim

This study aimed to explore the incidence of subjective well-being in mothers of children with sleep problems and whether implementing two behavioural sleep interventions changed their well-being.

Setting

The research was conducted in a community setting, with parents voluntarily approaching a sleep consultancy based in South Africa.

Method

Using data from 119 mothers voluntarily approaching a sleep consultancy in South Africa, a pre-test-post-test design was employed to investigate changes in life satisfaction, affect, couple satisfaction, perceived stress and depression approximately 3 weeks after implementation of a sleep intervention.

Results

Results indicate that mothers of children with sleep problems experienced moderate to high life satisfaction and positive affect although the presence of moderate negative affect, couple satisfaction and stress and mild depression suggest possible decreased subjective well-being.

Conclusion

Findings suggest implementation of graduated extinction and extinction with parental presence sleep interventions may improve life satisfaction, affect, stress and depression but not couple satisfaction in the short-term.

Contribution

This study contributes towards understanding the effect of sleep loss on the subjective well-being of mothers and provides preliminary evidence regarding the benefits of two sleep interventions for improving maternal subjective well-being.

Interventions to increase sleep duration in young people: A systematic review

This systematic review explored the outcomes of current interventions to increase sleep duration in healthy young people (14-25 years). Nine databases were systematically searched, and 26 studies were included in this review. Quality assessment of the included studies was evaluated using two tools: the Newcastle-Ottawa scale, and Cochrane Risk of Bias. The interventions incorporated a range of strategies including behavioral (46.2%), educational (26.9%), a combination of behavioral and educational (15.4%), and other strategies such as physical therapy (11.5%). The findings indicate that behavioral and combination interventions were consistently effective in increasing sleep duration in healthy young people. Educational interventions alone were less effective at increasing young people's sleep duration. Of all the included studies, only one randomized control trial but none of the non-randomized trials were rated as good quality. Our findings suggest a combination of strategies with an emphasis on personalization of intervention could possibly maximize the chances of success at improving sleep duration in healthy young people. More high-quality studies with long-term assessments (≥ 6 months) should be conducted to test the efficacy and durability of interventions to increase sleep duration in young people, as well as the clinical implications to mental and physical health.

Regulation of dendritic spines in the amygdala following sleep deprivation

The amygdala is a hub of emotional circuits involved in the regulation of cognitive and emotional behaviors and its critically involved in emotional reactivity, stress regulation, and fear memory. Growing evidence suggests that the amygdala plays a key role in the consolidation of emotional memories during sleep. Neuroimaging studies demonstrated that the amygdala is selectively and highly activated during rapid eye movement sleep (REM) and sleep deprivation induces emotional instability and dysregulation of the emotional learning process. Regulation of dendritic spines during sleep represents a morphological correlate of memory consolidation. Several studies indicate that dendritic spines are remodeled during sleep, with evidence for broad synaptic downscaling and selective synaptic upscaling in several cortical areas and the hippocampus. Currently, there is a lack of information regarding the regulation of dendritic spines in the amygdala during sleep. In the present work, we investigated the effect of 5 h of sleep deprivation on dendritic spines in the mouse amygdala. Our data demonstrate that sleep deprivation results in differential dendritic spine changes depending on both the amygdala subregions and the morphological subtypes of dendritic spines. We observed decreased density of mushroom spines in the basolateral amygdala of sleep deprived mice, together with increased neck length and decreased surface area and volume. In contrast, we observed greater densities of stubby spines in sleep deprived mice in the central amygdala, indicating that downscaling selectively occurs in this spine type. Greater neck diameters for thin spines in the lateral and basolateral nuclei of sleep deprived mice, and decreases in surface area and volume for mushroom spines in the basolateral amygdala compared to increases in the cental amygdala provide further support for spine type-selective synaptic downscaling in these areas during sleep. Our findings suggest that sleep promotes synaptic upscaling of mushroom spines in the basolateral amygdala, and downscaling of selective spine types in the lateral and central amygdala. In addition, we observed decreased density of phosphorylated cofilin immunoreactive and growth hormone immunoreactive cells in the amygdala of sleep deprived mice, providing further support for upscaling of dendritic spines during sleep. Overall, our findings point to region-and spine type-specific changes in dendritic spines during sleep in the amygdala, which may contribute to consolidation of emotional memories during sleep.

Sleep deprivation altered encoding of basolateral amygdala on fear acquisition

Sleep deprivation (SD) may lead to the development of fear- and anxiety-related emotional disorders. However, the neural mechanisms underlying the effects of SD on fear acquisition are unclear. Here, we tested whether and how SD influences the behavioral and neural manifestations of fear acquisition. We found that subjective fear ratings and objective fear indices (skin conductance response [SCR]) in the SD group were greater than those in the control group during fear acquisition, suggesting that SD facilitated fear acquisition (nSD = 18 and ncontrol = 23 for self-reported rating analysis; nSD = 10 and ncontrol = 10 for SCR analysis). Neuroimaging data showed that the SD group exhibited stronger activity in the left basolateral amygdala (BLA) and left superficial amygdala (SFA). Moreover, the left BLA activity, which positively correlated with the objective fear indices, significantly mediated the effect of SD on fear acquisition. Together, the present findings indicate that SD facilitates fear acquisition by augmenting threat-specific encoding in the BLA, which may be a potential biomarker of the risk of developing fear-related disorders under traumatic and distressing situations.

Patterns of risk-Using machine learning and structural neuroimaging to identify pedophilic offenders

Background

Child sexual abuse (CSA) has become a focal point for lawmakers, law enforcement, and mental health professionals. With high prevalence rates around the world and far-reaching, often chronic, individual, and societal implications, CSA and its leading risk factor, pedophilia, have been well investigated. This has led to a wide range of clinical tools and actuarial instruments for diagnosis and risk assessment regarding CSA. However, the neurobiological underpinnings of pedosexual behavior, specifically regarding hands-on pedophilic offenders (PO), remain elusive. Such biomarkers for PO individuals could potentially improve the early detection of high-risk PO individuals and enhance efforts to prevent future CSA.

Aim

To use machine learning and MRI data to identify PO individuals.

Methods

From a single-center male cohort of 14 PO individuals and 15 matched healthy control (HC) individuals, we acquired diffusion tensor imaging data (anisotropy, diffusivity, and fiber tracking) in literature-based regions of interest (prefrontal cortex, anterior cingulate cortex, amygdala, and corpus callosum). We trained a linear support vector machine to discriminate between PO and HC individuals using these WM microstructure data. Post hoc, we investigated the PO model decision scores with respect to sociodemographic (age, education, and IQ) and forensic characteristics (psychopathy, sexual deviance, and future risk of sexual violence) in the PO subpopulation. We assessed model specificity in an external cohort of 53 HC individuals.

Results

The classifier discriminated PO from HC individuals with a balanced accuracy of 75.5% (sensitivity = 64.3%, specificity = 86.7%, P ₅₀₀₀ = 0.018) and an out-of-sample specificity to correctly identify HC individuals of 94.3%. The predictive brain pattern contained bilateral fractional anisotropy in the anterior cingulate cortex, diffusivity in the left amygdala, and structural prefrontal cortex-amygdala connectivity in both hemispheres. This brain pattern was associated with the number of previous child victims, the current stance on sexuality, and the professionally assessed risk of future sexual violent reoffending.

Conclusion

Aberrant white matter microstructure in the prefronto-temporo-limbic circuit could be a potential neurobiological correlate for PO individuals at high-risk of reoffending with CSA. Although preliminary and exploratory at this point, our findings highlight the general potential of MRI-based biomarkers and particularly WM microstructure patterns for future CSA risk assessment and preventive efforts.

Bidirectional associations between nightly sleep and daily happiness and negative mood in adolescents

This study examined bidirectional associations between daily happiness and negative mood and subjective and objective sleep measures. Participants were 311 adolescents (M_age = 17.37 years; 51.8% female; 59.2% White/European American, 38.6% Black/African American, 1% Hispanic/Latinx American, 1.4% multi‐racial; 19.3% below poverty line) observed over a 7‐day period (2017–2018) using sleep diaries and actigraphy. Daily negative mood was related to greater subjective sleep/wake problems, and happiness was related to lower subjective sleep/wake problems. Conversely, shorter self‐reported sleep duration was related to higher negative mood the next day. For actigraphy measures, daily negative mood was related to greater sleep duration and efficiency, whereas happiness was related to lower sleep efficiency. Differences in associations based on subjective versus objective sleep measures are discussed.

Interactions between Sleep and Emotions in Humans and Animal Models

Recently, increased interest and efforts were observed in describing the possible interaction between sleep and emotions. Human and animal model studies addressed the implication of both sleep patterns and emotional processing in neurophysiology and neuropathology in suggesting a bidirectional interaction intimately modulated by complex mechanisms and factors. In this context, we aimed to discuss recent evidence and possible mechanisms implicated in this interaction, as provided by both human and animal models in studies. In addition, considering the affective component of brain physiological patterns, we aimed to find reasonable evidence in describing the two-way association between comorbid sleep impairments and psychiatric disorders. The main scientific literature databases (PubMed/Medline, Web of Science) were screened with keyword combinations for relevant content taking into consideration only English written papers and the inclusion and exclusion criteria, according to PRISMA guidelines. We found that a strong modulatory interaction between sleep processes and emotional states resides on the activity of several key brain structures, such as the amygdala, prefrontal cortex, hippocampus, and brainstem nuclei. In addition, evidence suggested that physiologically and behaviorally related mechanisms of sleep are intimately interacting with emotional perception and processing which could advise the key role of sleep in the unconscious character of emotional processes. However, further studies are needed to explain and correlate the functional analysis with causative and protective factors of sleep impairments and negative emotional modulation on neurophysiologic processing, mental health, and clinical contexts.

Can People Sleep Too Much? Effects of Extended Sleep Opportunity on Sleep Duration and Timing

Many people are concerned about whether they are getting "enough" sleep, and if they can "sleep too much." These concerns can be approached scientifically using experiments probing long-term (i.e., multi-night) sleep homeostatic processes, since homeostatic processes move the system toward its physiological setpoint (i.e., between "not enough" and "too much"). We analyzed sleep data from two human studies with sleep opportunities much longer than people usually stay in bed (i.e., conditions in which sleep homeostatic responses could be documented): sleep opportunities were 14-16 h per day for 3-28 days. Across the nights of the extended sleep opportunities, total sleep duration, Rapid Eye Movement (REM) sleep duration and non-REM sleep durations decreased and sleep latency increased. Multiple nights were required to reach approximately steady-state values. These results suggest a multi-day homeostatic sleep process responding to self-selected insufficient sleep duration prior to the study. Once steady state-values were reached, there were large night-to-night variations in total sleep time and other sleep metrics. Our results therefore answer these concerns about sleep amount and are important for understanding the basic physiology of sleep and for two sleep-related topics: (i) the inter-individual and intra-individual variability are relevant to understanding "normal" sleep patterns and for people with insomnia and (ii) the multiple nights of sleep required for recovery from insufficient sleep from self-selected sleep loss is important for public health and other efforts for reducing the adverse effects of sleep loss on multiple areas of physiology.

REM Sleep: An Unknown Indicator of Sleep Quality

Standard polysomnographic analysis of sleep has not provided evidence of an objective measure of sleep quality; however, factors such as sleep duration and sleep efficiency are those more consistently associated with the subjective perception of sleep quality. Sleep reduction as currently occurs in our 24/7 society has had a profound impact on sleep quality; the habitual sleep period should fit within what is a limited nighttime window and may not be sufficient to satisfy the whole sleep process; moreover, the use of artificial light during the evening and early night hours can delay and disturb the circadian rhythms, especially affecting REM sleep. The correct phase relationship of the sleep period with the circadian pacemaker is an important factor to guarantee adequate restorative sleep duration and sleep continuity, thus providing the necessary background for a good night's sleep. Due to the fact that REM sleep is controlled by the circadian clock, it can provide a window-like mechanism that defines the termination of the sleep period when there is still the necessity to complete the sleep process (not only wake-related homeostasis) and to meet the circadian end of sleep timing. An adequate amount of REM sleep appears necessary to guarantee sleep continuity, while periodically activating the brain and preparing it for the return to consciousness.

The Associations Between Daily Activities and Affect: a Compositional Isotemporal Substitution Analysis

BACKGROUND

Daily activities are associated with affective experiences. A 24-h day can be separated into five mutually exclusive activity types: sleep, awake in bed, moderate-to-vigorous physical activity (MVPA), light-intensity physical activity (LIPA), and sedentary behavior (SB). Most research has examined these activities independently and not collectively, yet increased time in one activity must be offset by decreasing other activities. Using compositional isotemporal substitution analyses, this study examined the associations between time spent in daily activities and affect, including both high and low arousal positive and negative affect.

METHOD

Across three separate studies, daily activities and affect were measured throughout 7-15 days (M_days = 10) in 361 healthy community adults (72.5% females, M_age = 22.79 years). Activities were objectively assessed using accelerometry and self-reported affect was assessed using repeated ecological momentary assessments. Minutes spent in each activity and affect values across the three studies were averaged for each participant.

RESULTS

Longer sleep duration at the expense of time awake in bed was associated with lower high arousal negative affect (e.g., nervousness, b =  - 0.24, p = .007). More MVPA at the expense of LIPA or SB was associated with higher high arousal positive affect (e.g., happiness, b = 0.35, p = .027). Activity composition was not associated with low arousal positive or negative affect (all p ≥ .06).

CONCLUSION

Associations between 24-h activity composition and affect differed based on types of activities, types of affect, and the interrelationships between activities within the composition. Findings can aid interventions to develop integrated guidance on the optimal activity patterns for mental health.

Residual, differential neurobehavioral deficits linger after multiple recovery nights following chronic sleep restriction or acute total sleep deprivation

STUDY OBJECTIVES

The amount of recovery sleep needed to fully restore well-established neurobehavioral deficits from sleep loss remains unknown, as does whether the recovery pattern differs across measures after total sleep deprivation (TSD) and chronic sleep restriction (SR).

METHODS

In total, 83 adults received two baseline nights (10-12-hour time in bed [TIB]) followed by five 4-hour TIB SR nights or 36-hour TSD and four recovery nights (R1-R4; 12-hour TIB). Neurobehavioral tests were completed every 2 hours during wakefulness and a Maintenance of Wakefulness Test measured physiological sleepiness. Polysomnography was collected on B2, R1, and R4 nights.

RESULTS

TSD and SR produced significant deficits in cognitive performance, increases in self-reported sleepiness and fatigue, decreases in vigor, and increases in physiological sleepiness. Neurobehavioral recovery from SR occurred after R1 and was maintained for all measures except Psychomotor Vigilance Test (PVT) lapses and response speed, which failed to completely recover. Neurobehavioral recovery from TSD occurred after R1 and was maintained for all cognitive and self-reported measures, except for vigor. After TSD and SR, R1 recovery sleep was longer and of higher efficiency and better quality than R4 recovery sleep.

CONCLUSIONS

PVT impairments from SR failed to reverse completely; by contrast, vigor did not recover after TSD; all other deficits were reversed after sleep loss. These results suggest that TSD and SR induce sustained, differential biological, physiological, and/or neural changes, which remarkably are not reversed with chronic, long-duration recovery sleep. Our findings have critical implications for the population at large and for military and health professionals.

Feasibility, acceptability and affective consequences of at-home sleep extension in young women with depressive symptoms: A pilot study

Insufficient sleep is common in young adults and has meaningful consequences for daytime functioning, including increased sleepiness, affective disruption and depressive symptoms. This study provides a preliminary evaluation of the feasibility, acceptability and affective consequences of extended sleep opportunity in young women with insufficient sleep and depressive symptoms. Participants were 32 women, 18-22 years of age, who regularly obtained less than 8-hr sleep/night and had daytime sleepiness and depressive symptoms at or above population averages. Participants were asked to maintain a sleep schedule of their typical duration for 7 days and were then randomly assigned to either extend sleep opportunity (ESO) by 90 min per night or maintain typical sleep opportunity (TSO), for the next 7 days. Sleep characteristics and daytime sleepiness were measured using continuous actigraphy and daily sleep diary, and affect, stress and depressive symptoms were assessed with daily and weekly questionnaires. Extended sleep opportunity increased sleep duration by over 1 hr, improved morning sleepiness and positive affect, and diminished anhedonia and depressive symptoms in study completers (n = 11 ESO, 11 TSO). However, 31.3% of participants (n = 10) were withdrawn from the study due to difficulty maintaining the sleep schedule. These results provide initial evidence that sleep extension is beneficial for young women who usually have inadequate sleep and mood disruption and can maintain a consistent sleep schedule. If extending sleep opportunity improves sleep, daytime sleepiness and affect in young adults who typically have insufficient sleep, it could broaden the range of interventions for sleep and mental wellness.

Irregular sleep habits, regional grey matter volumes, and psychological functioning in adolescents

Changing sleep rhythms in adolescents often lead to sleep deficits and a delay in sleep timing between weekdays and weekends. The adolescent brain, and in particular the rapidly developing structures involved in emotional control, are vulnerable to external and internal factors. In our previous study in adolescents at age 14, we observed a strong relationship between weekend sleep schedules and regional medial prefrontal cortex grey matter volumes. Here, we aimed to assess whether this relationship remained in this group of adolescents of the general population at the age of 16 (n = 101; mean age 16.8 years; 55% girls). We further examined grey matter volumes in the hippocampi and the amygdalae, calculated with voxel-based morphometry. In addition, we investigated the relationships between sleep habits, assessed with self-reports, and regional grey matter volumes, and psychological functioning, assessed with the Strengths and Difficulties Questionnaire and tests on working memory and impulsivity. Later weekend wake-up times were associated with smaller grey matter volumes in the medial prefrontal cortex and the amygdalae, and greater weekend delays in wake-up time were associated with smaller grey matter volumes in the right hippocampus and amygdala. The medial prefrontal cortex region mediated the correlation between weekend wake up time and externalising symptoms. Paying attention to regular sleep habits during adolescence could act as a protective factor against the emergence of psychopathology via enabling favourable brain development.

The Role of the Thalamus in the Neurological Mechanism of Subjective Sleepiness: An fMRI Study

PURPOSE

The thalamus, the region that forms the attentional network and transmits external sensory signals to the entire brain, is important for sleepiness. Herein, we examined the relationship between activity in the thalamus-seed brain network and subjective sleepiness.

MATERIALS AND METHODS

Fifteen healthy male participants underwent an experiment comprising a baseline evaluation and two successive interventions, a 9-day sleep extension followed by 1-night total sleep deprivation. Pre- and post-intervention tests included the Karolinska sleepiness scale and neuroimaging for arterial spin labeling and functional connectivity. We examined the association between subjective sleepiness and the functional magnetic resonance imaging indices.

RESULTS

The functional connectivity between the left or right thalamus and various brain regions displayed a significant negative association with subjective sleepiness, and the functional connectivity between the left and right thalamus displayed a significant positive association with subjective sleepiness. The graph theory analysis indicated that the number of positive functional connectivity related to the thalamus showed a strong negative association with subjective sleepiness, and conversely, the number of negative functional connectivity showed a positive association with subjective sleepiness. Arterial spin labeling analysis indicated that the blood flow in both the left and right thalami was significantly negatively associated with subjective sleepiness. Functional connectivity between the anterior cingulate cortex and salience network areas of the left insular cortex, and that between the anterior and posterior cingulate cortices showed a strong positive and negative association with subjective sleepiness, respectively.

CONCLUSION

Subjective sleepiness and the thalamic-cortical network dynamics are strongly related, indicating the application of graph theory to study sleepiness and consciousness. These results also demonstrate that resting functional connectivity largely reflects the "state" of the subject, suggesting that the control of sleep and conscious states is essential when using functional magnetic resonance imaging indices as biomarkers.

Effect of cognitive load and emotional valence of distractors on performance during sleep extension and subsequent sleep deprivation

Study Objectives

The purpose of the present study was to assess the extent to which sleep extension followed by sleep deprivation impacts performance on an attentional task with varying cognitive and attentional demands that influence decisions.

Methods

Task performance was assessed at baseline, after 1 week of sleep extension, and after 40 h of total sleep deprivation.

Results

One week of sleep extension resulted in improved performance, particularly for high cognitive load decisions regardless of the emotional salience of attentional distractors. Those who extended sleep the most relative to their habitual sleep duration showed the greatest improvement in general performance during sleep extension. However, a higher percentage of time spent in slow-wave sleep (SWS) on the last night of the sleep extension phase was negatively correlated with performance on more difficult high cognitive load items, possibly reflecting a relatively higher level of residual sleep need. Sleep deprivation generally resulted in impaired performance, with a nonsignificant trend toward greater performance decrements in the presence of emotionally salient distractors. Performance overall, but specifically for high cognitive load decisions, during total sleep deprivation was negatively correlated with longer sleep and higher SWS percentage during subsequent recovery sleep.

Conclusions

The present findings suggest two possibilities: those who performed relatively poorly during sleep deprivation were more vulnerable because (1) they utilized mental resources (i.e. accrued sleep debt) at a relatively faster rate during wakefulness, and/or (2) they failed to “pay down” pre-study sleep debt to the same extent as better-performing participants during the preceding sleep extension phase.

Integrating sleep, neuroimaging, and computational approaches for precision psychiatry

In advancing precision psychiatry, we focus on what imaging technology and computational approaches offer for the future of diagnostic subtyping and personalized tailoring of interventions for sleep impairment in mood and anxiety disorders. Current diagnostic criteria for mood and anxiety tend to lump different forms of sleep disturbance together. Parsing the biological features of sleep impairment and brain circuit dysfunction is one approach to identifying subtypes within these disorders that are mechanistically coherent and offer targets for intervention. We focus on two large-scale neural circuits implicated in sleep impairment and in mood and anxiety disorders: the default mode network and negative affective network. Through a synthesis of existing knowledge about these networks, we pose a testable framework for understanding how hyper- versus hypo-engagement of these networks may underlie distinct features of mood and sleep impairment. Within this framework we consider whether poor sleep quality may have an explanatory role in previously observed associations between network dysfunction and mood symptoms. We expand this framework to future directions including the potential for connecting circuit-defined subtypes to more distal features derived from digital phenotyping and wearable technologies, and how new discovery may be advanced through machine learning approaches.

Poor sleep quality at baseline is associated with increased aggression over one year in forensic psychiatric patients

OBJECTIVE

In forensic psychiatric patients, sleep problems as well as impulsivity and aggression are highly prevalent, yet studies on their association over time are lacking. This study investigates the association between sleep quality and changes in impulsivity and aggression in forensic psychiatric patients over one year.

METHODS

Data were drawn from an ongoing prospective observational study in adult forensic psychiatric patients admitted to a forensic treatment facility between October 2006 and January 2018. Validated self-reports and observational instruments were used to assess sleep quality, impulsivity and aggression upon admission to the hospital and after one year. Linear regression analyses were performed to examine the association between sleep quality, impulsivity and aggression. All models were adjusted for baseline values of outcome measures, demographic features and general psychopathology.

RESULTS

Data from 83 men (age 37.7 ± 11.7 years) with completed consecutive measurements were analyzed. Poor sleep quality was associated with increased self-reported aggression (β = 1.08; 95% CI, 0.38-1.78). This association was positively confounded by general psychopathology, indicating that sleep quality is specifically related to self-reported aggression instead of being part of general psychopathology (adjusted β = 1.18; 95% CI, 0.39-1.97). Poor sleep quality was not associated with changes in self-reported impulsivity, clinician-rated impulsivity or clinician-rated hostility in this population.

CONCLUSION

Poor sleep quality was associated with an increase in self-reported aggression over one year in male forensic psychiatric patients. Early evaluation and treatment of sleep problems in (forensic) psychiatric patients may play an important role in reducing the risk of aggressive behavior.

Differences in workday sleep fragmentation, rest-activity cycle, sleep quality, and activity level among nurses working different shifts

Schedule changes associated with rotating shifts can interfere with the circadian rhythms of nurses and thereby affect their sleep duration, sleep quality, work efficiency, and work performance. The objectives of this study was to investigate differences in workday sleep fragmentation, rest-activity cycle, sleep quality, and activity level among nurses working different shifts. After filling out a basic information questionnaire and completing the Pittsburgh Sleep Quality Index (PSQI) questionnaire, participants were asked to wear an actigraph and keep sleep records for seven consecutive days. Data pertaining to wake after sleep onset (WASO), 24-hour autocorrelation coefficient (r24), and daytime activity mean was collected in order to investigate workday sleep fragmentation, rest-activity cycle, and daytime activity level. We obtained complete questionnaires and data from 191 nurses. Day- and evening-shift nurses had more regular workday rest-activity cycles than did night-shift nurses (F = 51.26, p < .001). After controlling for r24 coefficients, we determined that nurses who experienced greater workday sleep fragmentation had higher PSQI scores (β = .18, p = .008). After controlling for WASO times, we determined that nurses who had more regular rest-activity cycles on workdays had lower PSQI scores (β = - .16, p = .036). After controlling for shift type and WASO times, we determined that nurses with higher PSQI scores displayed lower activity levels (β = - .21, p = .015) and those with higher r24 coefficients displayed higher activity levels (β = .18, p = .040) on workdays. We then examined the causal path relationships. Among the shifts, only the day-shift nurses had a higher r24 (β = -.59, p < .001) than did the night-shift nurses; WASO exerted a significant impact on PSQI scores (β = .20, p = .002); r24 had a significant and negative influence on PSQI scores (β = -.38, p < .001), and PSQI scores significantly and negatively influenced workday activity levels (β = -.20, p = .006). This study determined that day- and evening-shift nurses enjoyed more regular and consistent rest-activity cycles than did night-shift nurses; nurses with greater workday sleep fragmentation and/or more irregular rest-activity cycles experienced poorer sleep quality; and nurses suffering from poorer sleep quality displayed lower daytime activity levels on workdays.

Associations between sleep disturbances, mental health outcomes and burnout in firefighters, and the mediating role of sleep during overnight work: A cross-sectional study

This study investigated whether sleep disorder risk and mental health outcomes in firefighters were associated with burnout, particularly emotional exhaustion, and examined the mediating role of sleep at work in these relationships. A secondary aim was to investigate associations between habitual sleep characteristics and burnout. North American firefighters (n = 6,307) completed the Maslach Burnout Inventory (emotional exhaustion, depersonalisation, personal accomplishment), and were screened for sleep disorders and self-reported current mental health conditions and sleep characteristics. Multiple logistic regression analyses examined associations between sleep, mental health outcomes and burnout. Firefighters screening positive for a sleep disorder, particularly insomnia, had increased risk of emotional exhaustion (adjusted odds ratio 3.78, 95% confidence interval 2.97-4.79). Firefighters self-reporting a current mental health condition were at greater risk of emotional exhaustion (adjusted odds ratio 3.45, 95% confidence interval 2.79-4.27). Sleep during overnight work mediated the impact of having a sleep disorder and mental health condition on high burnout. Sleepiness and sleep deficit (difference between required and actual sleep), even in firefighters without sleep disorder risk, were associated with depersonalisation (adjusted odds ratio 1.65, 95% confidence interval 1.34-2.03 and adjusted odds ratio 1.29, 95% confidence interval 1.06-1.57, respectively) and low personal accomplishment (adjusted odds ratio 1.25, 95% confidence interval 1.07-1.47 and adjusted odds ratio 1.17, 95% confidence interval 1.01-1.35, respectively). Sleep and mental health problems were associated with increased risk of burnout in firefighters, and sleep during overnight work mediated these relationships. The results suggest the need to examine the effectiveness of occupational interventions that improve the opportunity for sleep, together with screening for and treating sleep disorders, to reduce burnout risk.

Sleep extension reduces fatigue in healthy, normally-sleeping young adults

Objective

To assess the effects of one week of sleep extension on mood, fatigue and subjective sleepiness in normal-sleeping young adults.

Methods

Twenty-seven adults (age 24.4±5.4 years, 11 female) participated. At-home baseline sleep/wake patterns were recorded with wrist actigraphy for 14 days. This was followed by two nights of in-lab baseline sleep with 8 hours time in bed (TIB), then 7 nights with TIB extended to 10 hours (2100-0700 hours). Fatigue, mood, and sleepiness were assessed following the 2^nd and 9^th nights of in-laboratory sleep (i.e., 2 nights with 8hTIB and 7 nights with 10 hours TIB, respectively) using the Automated Neuropsychological Assessment Metric and Karolinska Sleepiness Scale. Paired t-tests were used to compare mood, fatigue, and sleepiness ratings between conditions.

Results

At-home wrist actigraphy revealed a mean nightly total sleep time (TST) of 7.53 +/- 0.88 hours of sleep per night. Mean in-lab baseline sleep duration (7.76 +/- 0.59) did not differ from at-home sleep. However, during sleep extension, mean TST was 9.36 +/- 0.37 hours per night, significantly more than during the in-lab baseline (p < .001). Following sleep extension, fatigue ratings were significantly reduced, relative to baseline (p = .03). However, sleep extension had no other significant effects on subjective ratings of mood or sleepiness.

Conclusions

Sleep extension resulted in reduced fatigue in healthy, normal-sleeping young adults, although subjective sleepiness and mood were not improved. Implications include the possibility that (a) the effects of sleep extension on various aspects of mood depend upon the extent to which those aspects of mood are made salient by the study design and methodology; and (b) sleep extension may prove beneficial to fatigue-related conditions such as “burnout.”

Effects of Duration and Midpoint of Sleep on Corticolimbic Circuitry in Youth

INTRODUCTION

Adequate sleep is essential for cognitive and emotion-related functioning, and 9 to 12 hr of sleep is recommended for children ages 6 to 12 years and 8 to 10 hr for children ages 13 to 18 years. However, national survey data indicate that older youth sleep for fewer hours and fall asleep later than younger youth. This shift in sleep duration and timing corresponds with a sharp increase in onset of emotion-related problems (e.g., anxiety, depression) during adolescence. Given that both sleep duration and timing have been linked to emotion-related outcomes, the present study tests the effects of sleep duration and timing, and their interaction, on resting-state functional connectivity (RS-FC) of corticolimbic emotion-related neural circuitry in children and adolescents.

METHODS

A total of 63 children and adolescents (6-17 years, 34 females) completed a weekend overnight sleep journal and a 10-min resting-state functional magnetic resonance imaging scan the next day (Sunday). Whole-brain RS-FC of the amygdala was computed, and the effects of sleep duration, timing (i.e., midpoint of sleep), and their interaction were explored using regression analyses.

RESULTS

Overall, we found that older youth tended to sleep later and for fewer hours than younger youth. Controlling for age, shorter sleep duration was associated with lower RS-FC between the amygdala and regions implicated in emotion regulation, including ventral anterior cingulate cortex, precentral gyrus, and superior temporal gyrus. Interestingly, midpoint of sleep was associated with altered connectivity in a distinct set of brain regions involved in interoception and sensory processing, including insula, supramarginal gyrus, and postcentral gyrus. Our data also indicate widespread interactive effects of sleep duration and midpoint on brain regions implicated in emotion regulation, sensory processing, and motor control.

CONCLUSION

These results suggest that both sleep duration and midpoint of sleep are associated with next-day RS-FC within corticolimbic emotion-related neural circuitry in children and adolescents. The observed interactive effects of sleep duration and timing on RS-FC may reflect how homeostatic and circadian process interact in the brain and explain the complex patterns observed with respect to emotional health when considering sleep duration and timing. Sleep-related changes in corticolimbic circuitry may contribute to the onset of emotion-related problems during adolescence.

The Amygdala, Sleep Debt, Sleep Deprivation, and the Emotion of Anger: A Possible Connection?

The association of sleep with emotions has long been studied. However, not much has been studied about the association of sleep deprivation and sleep debt with the emotion of anger. In this article, we focused on the association of sleep with anger. The results suggest that lack of sleep - sleep deprivation and sleep debt - both lead to the emotion of anger. Some hints about the involvement of the limbic system have been found. Yet, due to a lack of a quantity of evidence, we suggest that more studies are conducted on the same topic to help us have a more in-depth exploration of the association of lack of sleep with anger.