The Neurobiology of Sleep and Wakefulness

The Association between Insomnia and Orgasmic Difficulty for Prostate Cancer Patients - Implication to Sex Therapy

Sexual dysfunction and insomnia are common side effects of prostate cancer (PCa) treatment, but the link between these symptoms has not been explored. We explore here the association between various sexual parameters and insomnia symptoms in PCa patients. Data were collected via an online survey with recruitment through various PCa organizations. One hundred and forty two patients (age = 67.3 ± 8.9 years) completed the survey. The majority were in a relationship (84.6%), of Caucasian ethnicity (83.1%), and 33% had previously received androgen deprivation therapy (ADT). Control variables-age, number of comorbidities, past ADT use, body mass index, depression, anxiety, fatigue and daytime sleepiness-explained 58.2% of the variance for insomnia symptoms. Including orgasm difficulty in the models accounted for an additional 2.1% in the variance in insomnia symptoms. Conversely, the control variables listed above together with insomnia symptoms predicted 37.7% of the overall variance in orgasm difficulty in PCa patients. These data suggest that sexual rehabilitation programs for PCa patients should assess insomnia symptoms, and therapies to improve sexual function or sleep quality may be beneficial in both functions given the relationship between sleep and orgasm functions in this population.

Troubles psychotiques et troubles du sommeil : revue de la littérature

Contexte La disparition de la nomenclature des troubles du sommeil dits primaires ou secondaires, rendue obsolète par le Manuel diagnostique et statistique des troubles mentaux (DSM-5), représente bien l’engouement académique actuel pour ce domaine de recherche. Il est de plus en plus reconnu que les troubles du sommeil sont plus que de simples conséquences d’un trouble psychiatrique et qu’ils peuvent persister malgré un traitement adéquat de la condition comorbide et même précéder ou exacerber cette dernière. Les troubles du sommeil dans les troubles psychotiques, très fréquents, sont donc devenus un sujet d’actualité, représentant une cible d’intervention jusqu’ici sous-estimée.

Objectif Cet article vise à présenter l’état des connaissances actuelles sur la relation entre les troubles du sommeil et les troubles psychotiques ainsi que sur l’utilisation de la thérapie cognitivo-comportementale (TCC) pour traiter les troubles du sommeil dans ce contexte.

Méthode L’article fait une recension narrative de la littérature pour décrire la relation bidirectionnelle entre la psychose et les troubles du sommeil, les corrélations cliniques et les traitements ciblant l’insomnie chez les patients psychotiques.

Résultats Malgré la présence d’une relation entre les troubles du sommeil et les troubles psychotiques, les mécanismes neuronaux, hormonaux et socioculturels régissant cette relation demeurent encore incertains. Bien que l’association reliant les troubles du sommeil et les troubles psychotiques demeure à clarifier, les études démontrent qu’elle serait bidirectionnelle et peut engendrer un cercle vicieux où ces deux composantes s’aggravent mutuellement. Dans ce contexte de comorbidités, les modèles unifiés en TCC deviennent un traitement de choix, à condition d’adapter les protocoles de TCC pour insomnie (TCC-i) à une population avec trouble psychotique (TCC-ip).

Conclusion Malgré la complexité de la relation entre les troubles psychotiques et ceux du sommeil, la TCC-i a été démontrée efficace pour traiter les troubles du sommeil dans une population psychotique et pourrait, dans certains cas, permettre d’alléger la symptomatologie psychotique. De futures études sur ce domaine pourraient permettre le développement de protocoles de thérapie cognitivo-comportementale pour les troubles du sommeil mieux adaptés à la population avec troubles psychotiques.

Acute cognitive effects of the hypocretin receptor antagonist almorexant relative to zolpidem and placebo: a randomized clinical trial

STUDY OBJECTIVES

Hypnotic medications can adversely affect behavior during unanticipated awakenings during the night. Animals treated with the hypocretin (Hcrt) receptor antagonist almorexant (ALM) have less acute cognitive impairment compared to the GABAA receptor modulator zolpidem (ZOL). This study aimed to determine whether ALM produces less acute cognitive impairment than ZOL in human subjects.

METHODS

Healthy, young adult, unmedicated male and female subjects participated in a controlled trial of a single dose of ALM 100 mg (N = 48), ALM 200 mg (N = 53), ZOL 10 mg (N = 49), and placebo (PBO, N = 52).

RESULTS

ZOL and both doses of ALM produced similar levels of subjective sleepiness and impaired the ability of subjects to remain awake in a dark, low-stimulus setting relative to PBO. For most cognitive measures, performance under ZOL was significantly worse than ALM or PBO. For tasks involving verbal memory or visual-motor coordination, ZOL impaired performance, whereas the two doses of ALM were no different than PBO. For tasks involving higher-order executive function, ZOL produced impairment in processing speed and inhibitory control, whereas the two doses of ALM were no different than PBO. Performance decrements for ALM were less than ZOL but greater than PBO for some reaction time measures.

CONCLUSIONS

The data provide support for the hypothesis that Hcrt receptor antagonists produce less functional impairment than a benzodiazepine receptor agonist (BzRA). These observations are particularly relevant to patients treated with sedative-hypnotics who are at elevated risk for falls and other untoward events during the intended hours for sleep.

Sleep and Sex: A Review of the Interrelationship of Sleep and Sexuality Disorders in the Female Population, Through the Lens of Sleeping Beauty Syndrome

INTRODUCTION

For many, sleep and sex are crucial for physical, emotional, and mental well-being. Poor sleep quality is linked to a myriad of ailments from coronary artery disease to major depressive disorder. Likewise, a decrease in the frequency of sexual activity is associated with a decrease in self-rated health status. Kleine-Levin syndrome (KLS) is a rare sleep disorder that provides a unique lens to examine the intricate interplay between sleep and sex as it is one of the few sleep disorders defined by concomitant sexual dysfunction.

OBJECTIVES

This study reviews the literature on links between sleep disorders and sexuality with a focus on women's health followed by a case study of unusual patient with KLS with persistent genital arousal disorder.

METHODS

Literature searches were conducted for English language publications, including foreign language publications with English abstracts with ninety-five articles reviewed. The literature review is followed by a case report.

RESULTS

We review the known literature linking sleep and women's sexual health with a focus on insomnia, circadian rhythm sleep disorder, obstructive sleep apnea, restless leg syndrome, sexsomnia, and KLS. We then present a case of KLS-associated persistent genital arousal disorder, which was amenable to treatment with a multimodal approach aimed at symptomatic relief with intravaginal diazepam suppositories, topical clitoral lidocaine, and duloxetine.

CONCLUSION

This case highlights that hypersexuality and persistent arousal cannot effectively be treated in isolation but rather must be contextualized within a patient's broader medical history and diagnoses. Specifically, sleep quality and potential sleep disorders should be assessed for those presenting with sexual health complaints (and vice versa). Zwerling B, Keymeulen S, Krychman ML. Sleep and Sex: A Review of the Interrelationship of Sleep and Sexuality Disorders in the Female Population, Through the Lens of Sleeping Beauty Syndrome. Sex Med Rev 2021;9:221-229.

Cannabinoids, Endocannabinoids and Sleep

Sleep is a vital function of the nervous system that contributes to brain and bodily homeostasis, energy levels, cognitive ability, and other key functions of a variety of organisms. Dysfunctional sleep induces neural problems and is a key part of almost all human psychiatric disorders including substance abuse disorders. The hypnotic effects of cannabis have long been known and there is increasing use of phytocannabinoids and other formulations as sleep aids. Thus, it is crucial to gain a better understanding of the neurobiological basis of cannabis drug effects on sleep, as well as the role of the endogenous cannabinoid system in sleep physiology. In this review article, we summarize the current state of knowledge concerning sleep-related endogenous cannabinoid function derived from research on humans and rodent models. We also review information on acute and chronic cannabinoid drug effects on sleep in these organisms, and molecular mechanisms that may contribute to these effects. We point out the potential benefits of acute cannabinoids for sleep improvement, but also the potential sleep-disruptive effects of withdrawal following chronic cannabinoid drug use. Prescriptions for future research in this burgeoning field are also provided.

The Insomnia Plague in Fictional Macondo

Disease and medicine are found throughout Gabriel García Márquez's work. This article examines the insomnia plague described in the novel One Hundred Years of Solitude and performs a differential diagnosis exercise with conditions that affect both sleep and memory. The main finding is that the insomnia plague narrated by García Márquez, with its clinical manifestations, the sequence of symptoms, and its resolution, cannot be associated with any specific diagnosis. However, similarities to and differences from several clinical conditions are discussed, as well as the relation between the neurophysiologic phenomena of sleep and memory.

Association of orexin/hypocretin receptor gene (HCRTR1) with reward sensitivity, and interaction with gender

Orexins/hypocretins maintain wakefulness, increase appetite and participate in the coordination of stress response. We have recently provided evidence on the role of orexins in aggression, showing the association of the HCRTR1 genotype. (rs2271933 G > A; leading to amino acid substitution Ile408Val) with aggressiveness or breach of law in four independent cohorts. Aggressive behaviour can be reward driven and hence we have examined the association of HCRTR1 rs2271933 genotype with different aspects of reward sensitivity in the birth cohort representative Estonian Children Personality Behaviour and Health Study. HCRTR1 genotype was associated with reward sensitivity in a gender dependent manner. Male HCRTR1 A/A homozygotes had higher Openness to Rewards and the overall reward sensitivity score while, in contrast, female A/A homozygotes scored lower than G-allele carriers in Openness to Rewards. In the total sample, aggressiveness correlated positively with reward sensitivity, but this was on account of Insatiability by Reward. In contrast, the HCRTR1 A/A homozygotes had a positive association of aggressiveness and Openness to Rewards. Experience of stressful life events had a small but significant increasing effect on both aspects of reward sensitivity, and correlated in an anomalous way with reward sensitivity in the HCRTR1 A/A homozygotes. Conclusively, the higher aggressiveness of HCRTR1 A/A homozygotes appears based on a qualitative difference in sensitivity to rewards, in the form that suggests their lower ability to prevent responses to challenges being converted into overt aggression.

Sleep, brain development, and autism spectrum disorders: Insights from animal models

Sleep is an evolutionarily conserved and powerful drive, although its complete functions are still unknown. One possible function of sleep is that it promotes brain development. The amount of sleep is greatest during ages when the brain is rapidly developing, and sleep has been shown to influence critical period plasticity. This supports a role for sleep in brain development and suggests that abnormal sleep in early life may lead to abnormal development. Autism spectrum disorder (ASD) is the most prevalent neurodevelopmental disorder in the United States. It is estimated that insomnia affects 44%-86% of the ASD population, predicting the severity of ASD core symptoms and associated behavioral problems. Sleep problems impact the quality of life of both ASD individuals and their caregivers, thus it is important to understand why they are so prevalent. In this review, we explore the role of sleep in early life as a causal factor in ASD. First, we review fundamental steps in mammalian sleep ontogeny and regulation and how sleep influences brain development. Next, we summarize current knowledge gained from studying sleep in animal models of ASD. Ultimately, our goal is to highlight the importance of understanding the role of sleep in brain development and the use of animal models to provide mechanistic insight into the origin of sleep problems in ASD.

Alterations of neural network organization during REM sleep in women: implication for sex differences in vulnerability to mood disorders

BACKGROUND

Sleep plays an important role in vulnerability to mood disorders. However, despite the existence of sex differences in vulnerability to mood disorders, no study has yet investigated the sex effect on sleep network organization and its potential involvement in vulnerability to mood disorders. The aim of our study was to empirically investigate the sex effect on network organization during REM and slow-wave sleep using the effective connectivity measured by Granger causality.

METHODS

Polysomnographic data from 44 healthy individuals (28 men and 16 women) recruited prospectively were analysed. To obtain the 19 × 19 connectivity matrix of all possible pairwise combinations of electrodes by Granger causality method from our EEG data, we used the Toolbox MVGC multivariate Granger causality. The computation of the network measures was realized by importing these connectivity matrices into EEGNET Toolbox.

RESULTS

In men and women, all small-world coefficients obtained are compatible with a small-world network organization during REM and slow-wave sleep. However, compared to men, women present greater small-world coefficients during REM sleep as well as for all EEG bands during this sleep stage, which indicates the presence of a small-world network organization less marked during REM sleep as well as for all EEG bands during this sleep stage in women. In addition, in women, these small-world coefficients during REM sleep as well as for all EEG bands during this sleep stage are positively correlated with the presence of subclinical symptoms of depression.

CONCLUSIONS

Thus, the highlighting of these sex differences in network organization during REM sleep indicates the presence of differences in the global and local processing of information during sleep between women and men. In addition, this small-world network organization less marked during REM sleep appears to be a marker of vulnerability to mood disorders specific to women, which opens up new perspectives in understanding sex differences in the occurrence of mood disorders.

Sleep disturbance in PTSD and other anxiety-related disorders: an updated review of clinical features, physiological characteristics, and psychological and neurobiological mechanisms

The current report provides an updated review of sleep disturbance in posttraumatic stress disorder and anxiety-related disorders. First, this review provides a summary description of the unique and overlapping clinical characteristics and physiological features of sleep disturbance in specific DSM anxiety-related disorders. Second, this review presents evidence of a bidirectional relationship between sleep disturbance and anxiety-related disorders, and provides a model to explain this relationship by integrating research on psychological and neurocognitive processes with a current understanding of neurobiological pathways. A heuristic neurobiological framework for understanding the bidirectional relationship between abnormalities in sleep and anxiety-related brain pathways is presented. Directions for future research are suggested.

Optogenetic/Chemogenetic Activation of GABAergic Neurons in the Ventral Tegmental Area Facilitates General Anesthesia via Projections to the Lateral Hypothalamus in Mice

The ventral tegmental area (VTA) reportedly regulates sleep and wakefulness through communication with the lateral hypothalamus (LH). It has also been suggested that adequate anesthesia produced by administration of chloral hydrate, ketamine, or halothane significantly reduces the GABAergic neuronal firing rate within the VTA. However, the exact effects on GABAergic neurons in the VTA and the mechanisms through which these neurons modulate anesthesia through associated neural circuits is still unclear. Here, we used optogenetic and chemogenetic methods to specifically activate or inhibit GABAergic neuronal perikarya in the VTA or their projections to the LH in Vgat-Cre mice. Electroencephalogram (EEG) spectral analyses and burst suppression ratio (BSR) calculations were conducted following administration of 0.8 or 1.0% isoflurane, respectively; and loss of righting reflex (LORR), recovery of righting reflex (RORR), and anesthesia sensitivity were assessed under 1.4% isoflurane anesthesia. The results showed that activation of GABAergic neurons in the VTA increased delta wave power from 40.0 to 46.4% (P = 0.006) and decreased gamma wave power from 15.2 to 11.5% (P = 0.017) during anesthesia maintenance. BSR was increased from 51.8 to 68.3% (P = 0.017). Induction time (LORR) was reduced from 333 to 290 s (P = 0.019), whereas arousal time (RORR) was prolonged from 498 to 661 s (P = 0.007). Conversely, inhibition of VTA GABAergic neurons led to opposite effects. In contrast, optical activation of VTA-LH GABAergic projection neurons increased power of slow delta waves from 44.2 to 48.8% (P = 0.014) and decreased that of gamma oscillations from 10.2 to 8.0%. BSR was increased from 39.9 to 60.2% (P = 0.0002). LORR was reduced from 330 to 232 s (P = 0.002), and RORR increased from 396 to 565 s (P = 0.007). Optical inhibition of the projection neurons caused opposite effects in terms of both the EEG spectrum and the BSR, except that inhibition of this projection did not accelerate arousal time. These results indicate that VTA GABAergic neurons could facilitate the anesthetic effects of isoflurane during induction and maintenance while postponing anesthetic recovery, at least partially, through modulation of their projections to the LH.

Therapeutic Approaches for the Management of Sleep Disorders in Geriatric Population

OBJECTIVE

Aging is a natural biological phenomenon that occurs in human beings. With increasing of age, there is an appearance of deleterious changes related to progression onto pathological conditions, including hypertension, heart disease, diabetes, hearing and vision impairments, as well as sleep disorders. It is important to recognize that some sleep disturbances reported by aged subjects include insomnia, obstructive sleep apnea, restless legs syndrome, among others. Moreover, accumulating evidence indicates that coexistence of medical issues with sleep disorders constitutes clinical challenges for treatment of comorbidities in elderly. Here, we have attempted to review and summarize the available literature that assesses the sleep disturbances in aging. In addition, we highlight the management of sleep disorders associated with aging. Due to the particular health condition of aged adults, the development of effective pharmacological interventions for sleep disorders treatment in aging is warranted.

METHODS

Review of studies retrieved from the PubMed.

RESULTS

The sleep-wake cycle includes abnormalities classified as sleep disorders. Comorbidity between sleep disturbances and aging-related health issues will represent a public health challenge to be addressed in the near future. Moreover, this scenario will suggest an area that requires further drug investigation and design of new pharmacological and pharmaceutical strategies to treat sleep disorders in the elderly population.

CONCLUSION

The review highlights the sleep disturbances in aging. We focus on current knowledge in medicinal chemistry and further design of new treatments tools for managing sleep disturbances in the aged population.

Hypothalamic orexin and mechanistic target of rapamycin activation mediate sleep dysfunction in a mouse model of tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a genetic disease related to hyperactivation of the mechanistic target of rapamycin (mTOR) pathway and manifested by neurological symptoms, such as epilepsy and sleep disorders. The pathophysiology of sleep dysfunction is poorly understood and is likely multifactorial, but may involve intrinsic biological regulators in the brain. Here, we characterized a mouse model of sleep disorders in TSC and investigated mechanisms of sleep dysfunction in this conditional knockout model involving inactivation of the Tsc1 gene in neurons and astrocytes (Tsc1^GFAPCKO mice). Sleep studies utilizing EEG, EMG, and behavioral analysis found that Tsc1^GFAPCKO mice have decreased REM sleep and impaired sleep-wake differentiation between light and dark phases. mTOR activity and orexin expression were increased in hypothalamic sections and cultured hypothalamic neurons from Tsc1^GFAPCKO mice. Both the sleep abnormalities and increased orexin expression in Tsc1^GFAPCKO mice were reversed by rapamycin treatment, indicating their dependence on mTOR activation. An orexin antagonist, suvorexant, also restored normal REM levels in Tsc1^GFAPCKO mice. These results identify a novel mechanistic link between mTOR and orexin in the hypothalamus related to sleep dysfunction and suggest a targeted therapeutic approach to sleep disorders in TSC.

Alterations of neural network organisation during rapid eye movement sleep and slow-wave sleep in major depression: Implications for diagnosis, classification, and treatment

The aim of this study was to empirically investigate the network organisation during rapid eye movement sleep (REMS) and slow-wave sleep (SWS) using the effective connectivity measured using the Granger causality to identify new potential biomarkers for the diagnosis, classification, and potential favourable response to treatment in major depression. Polysomnographic data were analysed from 24 healthy individuals and 16 major depressed individuals recruited prospectively. To obtain the 19×19 connectivity matrix of all possible pairwise combinations of electrodes by the Granger causality method from our electroencephalographic data, we used the Toolbox MVGC multivariate Granger causality. The computation of network measures was realised by importing these connectivity matrices into the EEGNET Toolbox. Major depressed individuals (versus healthy individuals) and those with endogenous depression (versus those with neurotic depression) present alterations of small-world network organisation during REMS, whereas major depressed individuals with potential favourable response to electroconvulsive therapy (versus those with potential unfavourable response) have a less efficient small-world network organisation during SWS. Thus, alterations in network organisation during REMS could be biomarkers for the diagnosis and classification of major depressive episodes, whereas alterations of network organisation during SWS could be a biomarker to predict potential favourable response to treatment by electroconvulsive therapy.

The Effect of Hypnotics on Sleep Quality and Cognitive Function in Patients with Brain Tumors

Objective

We investigated the effect of hypnotics on sleep quality, cognitive function, and depressive mood in patients with insomnia following brain tumor resection.

Methods

From patients who underwent brain tumor resection, we recruited 10 patients with insomnia who received hypnotics for more than 1 week during a 3-week follow-up period (insomnia group). We also recruited 12 control patients with brain tumors but without insomnia (control group). We evaluated sleep quality at baseline and 3 weeks later using the Insomnia Severity Index (ISI), the Pittsburgh Sleep Quality Index (PSQI), the Stanford Sleepiness Scale (SSS), and the Epworth Sleepiness Scale (ESS) and investigated cognitive function and depression using the Computerized Neuropsychological Test and the Beck Depression Inventory (BDI).

Results

At baseline, SSS, ISI, PSQI, and BDI scores were significantly higher and visual continuous performance test (VCPT) and auditory continuous performance test (ACPT) scores were significantly lower in the insomnia than in the control group. Three weeks later, the patients who had received hypnotics had significantly higher ISI, PSQI, ESS, VCPT, ACPT, visual span forward and backward, and visual recognition test scores, and significantly lower BDI scores.

Conclusion

Quality of sleep in patients with insomnia following brain tumor resection was initially poor but improved significantly after taking hypnotic medication. Further, the hypnotic medications appeared to contribute to the amelioration of cognitive impairments and depressive moods in patients who previously underwent brain tumor resection. We thus recommend the use of hypnotics for patients with brain tumors with insomnia.

Propagations of spontaneous brain activity in awake rats

Slow propagations of spontaneous brain activity have been reported in multiple species. However, systematical investigation of the organization of such brain activity is still lacking. In this study, we analyzed propagations of spontaneous brain activity using a reference library of characteristic resting-state functional connectivity (RSFC) patterns in awake rodents. We found that transitions through multiple distinct RSFC patterns were reproducible not only in transition sequences but also in transition time delays. In addition, the organization of these transitions and their spatiotemporal dynamic patterns were revealed using a graphical model. We further identified prominent brain regions involved in these transitions. These results provide a comprehensive framework of brainwide propagations of spontaneous activity in awake rats. This study also offers a new tool to study the spatiotemporal dynamics of activity in the resting brain.

Increased Mmp/Reck Expression Ratio Is Associated with Increased Recognition Memory Performance in a Parkinson's Disease Animal Model

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder worldwide. Among its non-motor symptoms, sleep disorders are extremely common, being linked to cognitive and memory disruption. The microenvironment, particularly the extracellular matrix (ECM), is deeply involved in memory consolidation as well as in neuropathological processes, such as inflammation, damage to the blood-brain barrier and neuronal death. To better understand ECM dynamics in PD memory disturbances, we investigated the orchestrated expression of Mmps (Mmp-3, Mmp-7, and Mmp-9) and their modulators (Reck and Timp-3) in a rotenone-induced PD model. Also, we introduced an additional intervention in the memory process through rapid eye movement sleep deprivation (REMSD). We observed a REMSD-induced trend in reversing the memory impairment caused by rotenone administration. Associated to this phenotype, we observed a significant increase in Mmp-7/Reck and Mmp-9/Reck mRNA expression ratio in the substantia nigra and Mmp-9/Reck ratio in the hypothalamus. Moreover, the positive correlation of Mmp/Reck expression ratios between the substantia nigra and the striatum, observed upon rotenone infusion, was reversed by REMSD. Taken together, our results suggest a potential orchestrated association between an increase in Mmp-7 and Mmp-9/Reck expression ratios in the substantia nigra and a possible positive effect on cognitive performance in subjects affected by PD.

Selective Vulnerability of Brainstem Nuclei in Distinct Tauopathies: A Postmortem Study

The brainstem nuclei of the reticular formation (RF) are critical for regulating homeostasis, behavior, and cognition. RF degenerates in tauopathies including Alzheimer disease (AD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). Although the burden of phopho-tau inclusion is high across these diseases, suggesting a similar vulnerability pattern, a distinct RF-associated clinical phenotype in these diseases indicates the opposite. To compare patterns of RF selective vulnerability to tauopathies, we analyzed 5 RF nuclei in tissue from 14 AD, 14 CBD, 10 PSP, and 3 control cases. Multidimensional quantitative analysis unraveled discernable differences on how these nuclei are vulnerable to AD, CBD, and PSP. For instance, PSP and CBD accrued more tau inclusions than AD in locus coeruleus, suggesting a lower vulnerability to AD. However, locus coeruleus neuronal loss in AD was so extreme that few neurons remained to develop aggregates. Likewise, tau burden in gigantocellular nucleus was low in AD and high in PSP, but few GABAergic neurons were present in AD. This challenges the hypothesis that gigantocellular nucleus neuronal loss underlies REM behavioral disorders because REM behavioral disorders rarely manifests in AD. This study provides foundation for characterizing the clinical consequences of RF degeneration in tauopathies and guiding customized treatment.

Pharmacological treatment for insomnia in patients with major depressive disorder

INTRODUCTION

Insomnia in Major Depressive Disorder (MDD) is highly prevalent and associated with increased suffering and functional impairment. Effective, evidence-based treatments for insomnia in MDD are an unmet need in clinical practice.

AREAS COVERED

Herein, the authors provide a review of the clinical correlates, putative neurobiological mechanisms and treatment options for the management of insomnia in individuals with MDD.

EXPERT OPINION

Sleep disturbances in MDD should be recognized as at least one of the following: (1) a domain of depressive psychopathology; (2) a consequence of rhythm disruptions; (3) a manifestation of comorbidities of sleep disturbances; (4) a manifestation of the influence of sex hormones in the brain in MDD; (5) a general medical comorbidity; and (6) a side effect of antidepressant medications. Assessment of insomnia in clinical practices is routinely performed with the use of non-structured interviews. Other methods such as standardized questionnaires and sleep diaries, along with complementary methods such as actigraphy and polysomnography are more scarcely applied. Smartphones and personal devices offer a promising strategy with the use of passive, long lasting, and ecologically valid assessments despite the lack of studies specifically targeting insomnia in individuals with MDD. New therapeutic approaches are essential, including novel targets such as orexins/hypocretins and the endocannabinoid system.

The olfactory bulb: A link between environmental agents and narcolepsy

Narcolepsy with cataplexy is a lifelong sleep disorder associated with orexin/hypocretin deficiency in the central nervous system. In addition to a genetic predisposition, a variety of environmental factors, such as influenza viruses, have been implicated in the pathogenesis of the disease. In this article, a hypothesis is proposed that environmental agents access the olfactory bulb and trigger neuroinflammation, which in turn induces neurodegeneration of orexinergic neurons in the lateral hypothalamus and other neuronal subpopulations regulating the sleep-wake cycle, which triggers the development of narcolepsy.

Remembering to Forget: A Dual Role for Sleep Oscillations in Memory Consolidation and Forgetting

It has been known since the time of patient H. M. and Karl Lashley's equipotentiality studies that the hippocampus and cortex serve mnestic functions. Current memory models maintain that these two brain structures accomplish unique, but interactive, memory functions. Specifically, most modeling suggests that memories are rapidly acquired during waking experience by the hippocampus, before being later consolidated into the cortex for long-term storage. Sleep has been shown to be critical for the transfer and consolidation of memories in the cortex. Like memory consolidation, a role for sleep in adaptive forgetting has both historical precedent, as Francis Crick suggested in 1983 that sleep was for "reverse-learning," and recent empirical support. In this article I review the evidence indicating that the same brain activity involved in sleep replay associated memory consolidation is responsible for sleep-dependent forgetting. In reviewing the literature, it became clear that both a cellular mechanism for systems consolidation and an agreed upon general, as well as cellular, mechanism for sleep-dependent forgetting is seldom discussed or is lacking. I advocate here for a candidate cellular systems consolidation mechanism wherein changes in calcium kinetics and the activation of consolidative signaling cascades arise from the triple phase locking of non-rapid eye movement sleep (NREMS) slow oscillation, sleep spindle and sharp-wave ripple rhythms. I go on to speculatively consider several sleep stage specific forgetting mechanisms and conclude by discussing a notional function of NREM-rapid eye movement sleep (REMS) cycling. The discussed model argues that the cyclical organization of sleep functions to first lay down and edit and then stabilize and integrate engrams. All things considered, it is increasingly clear that hallmark sleep stage rhythms, including several NREMS oscillations and the REMS hippocampal theta rhythm, serve the dual function of enabling simultaneous memory consolidation and adaptive forgetting. Specifically, the same sleep rhythms that consolidate new memories, in the cortex and hippocampus, simultaneously organize the adaptive forgetting of older memories in these brain regions.

Application of gastrointestinal regulation in acupuncture treatment of insomnia based on the brain-gut axis theory

Gastrointestinal function is closely related to insomnia. The brain-gut axis theory provides a new way to regulate gastrointestinal function in the treatment of insomnia. By analyzing the nervous, endocrine, immune, and intestinal flora systems of the brain-gut axis that affects brain function as well as the regulatory effect of acupuncture and the traditional theoretical basis for the relationship of the brain-gut axis with the gastrointestinal tract and insomnia, we discuss the feasibility of acupuncture treatment of insomnia by regulating the gastrointestinal tract based on the brain-gut axis theory.

Sleep and weight-height development

OBJECTIVES

To describe the association between sleep duration and weight-height development in children and adolescents.

SOURCE OF DATA

A non-systematic search in the MEDLINE database was performed using the terms anthropometry, body composition, overweight, obesity, body mass index, growth, length, short stature, sleep, children, and infants and adolescents, limited to the last 5 years. The references cited in the revised articles were also reviewed, when relevant.

SYNTHESIS OF DATA

Sleep disorders are prevalent in the pediatric population. Among them, insomnia, which leads to a reduction in total sleep time, is the most prevalent disorder. Evidence found in the current literature allows the conclusion that sleep time reduction has a role in the current pandemic of overweight and obesity. Studies associating sleep deprivation and deficit in height growth are still insufficient.

CONCLUSIONS

The association between shorter sleep duration and risk of overweight and obesity is well established for all pediatric age groups. However, more evidence is needed to establish an association between insufficient sleep duration and height growth deficit. Pediatricians should include the encouragement of healthy sleep habits in their routine guidelines as an adjuvant in the prevention and management of excess weight.

Sex differences in sleep and sleep loss-induced cognitive deficits: The influence of gonadal hormones

Males and females can respond differentially to the same environmental stimuli and experimental conditions. Chronic sleep loss is a frequent and growing problem in many modern societies and has a broad variety of negative outcomes for health and well-being. While much has been done to explore the deleterious effects of sleep deprivation (SD) on cognition in both human and animal studies over the last few decades, very little attention has been paid to the part played by sex differences and gonadal steroids in respect of changes in cognitive functions caused by sleep loss. The effects of gonadal hormones on sleep regulation and cognitive performances are well established. Reduced gonadal function in menopausal women and elderly men is associated with sleep disturbances and cognitive decline as well as dementia, which suggests that sex steroids play a key role in modulating these conditions. Finding out whether there are sex differences in respect of the effect of insufficient sleep on cognition, and how neuroendocrine mediators influence cognitive impairment induced by SD could provide valuable insights into the best therapies for each sex. In this review, we aim to highlight the involvement of sex differences and gonadal hormone status on the severity of cognitive deficits induced by sleep deficiency in both human and animal studies.

The interplay between neuroendocrine and sleep alterations following traumatic brain injury

BACKGROUND

Sleep and endocrine disruptions are prevalent after traumatic brain injury (TBI) and are likely to contribute to morbidity.

OBJECTIVE

To describe the interaction between sleep and hormonal regulation following TBI and elucidate the impact that alterations of these systems have on cognitive responses during the posttraumatic chronic period.

METHODS

Review of preclinical and clinical literature describing long-lasting endocrine dysregulation and sleep alterations following TBI. The bidirectional relationship between sleep and hormones is described. Literature describing co-occurrence between sleep-wake disturbances and hormonal dysregulation will be presented. Review of literature describing cognitive effects of seep and hormones. The cognitive and functional impact of sleep disturbances and hormonal dysregulation is discussed within the context of TBI.

RESULTS/CONCLUSIONS

Sleep and hormonal alterations impact cognitive and functional outcome after TBI. Diagnosis and treatment of these disturbances will impact recovery following TBI and should be considered in the post-acute rehabilitative setting.

Impact of traumatic brain injury on sleep: an overview

Traumatic brain injury (TBI) is a global health problem that affects millions of civilians, athletes, and military personnel yearly. Sleeping disorders are one of the underrecognized sequalae even though they affect 46% of individuals with TBI. After a mild TBI, 29% of patients have insomnia, 25% have sleep apnea, 28% have hypersomnia, and 4% have narcolepsy. The type of sleep disturbance may also vary according to the number of TBIs sustained. Diffuse axonal injury within the sleep regulation system, disruption of hormones involved in sleep, and insults to the hypothalamus, brain stem, and reticular activating system are some of the proposed theories for the pathophysiology of sleep disorders after TBI. Genetic and anatomical factors also come to play in the development and severity of these sleeping disorders. Untreated sleep disturbances following TBI can lead to serious consequences with respect to an individual's cognitive functioning. Initial management focuses on conservative measures with progression to more aggressive options if necessary. Future research should attempt to establish the effectiveness of the treatments currently used, as well as identify manageable co-existing factors that could be exacerbating sleep disorders.

The influence of non-breathing-related sleep fragmentation on cognitive function in patients with cerebral small vessel disease

BACKGROUND

Cognitive impairment in patients with cerebral small vessel disease (CSVD) is common, but the pathogenic mechanism is not well understood. The situation of non-breathing-related sleep fragmentation in CSVD patients and its influence on cognitive impairment is not clear. The aim of this study was to investigate the influence of non-breathing-related sleep fragmentation on cognitive function in patients with CSVD.

METHODS

A group of 89 CSVD patients without breathing-related sleep disorders in the Department of Neurology, Third Affiliated Hospital of Sun Yat-sen University was enrolled. The patients underwent magnetic resonance scan, polysomnography, cognitive function evaluation using Montreal Cognitive Assessment scale (MoCA), and Mini-Mental State Examination. The patients were assigned to study group (arousal index [ArI] ≥26.8/hour) or control group (ArI <26.8/hour) based on the average level of ArI (mean =26.8, SD =7.5) at night, and the cognitive function of the patients in the two groups was analyzed.

RESULTS

The total MoCA score, the subscale scores of visuospatial ability and delayed recall in the study group were significantly lower than that in the control group (P<0.05). The cognitive impairment measured by MoCA was positively related to ArI level and %N-3 sleep according to the results of logistic regression (P<0.05).

CONCLUSION

Non-breathing-related sleep fragmentation is associated with cognitive impairment in CSVD patients, especially executive function and delayed recall ability.

Post-Hoc Analyses of the Effects of Baseline Sleep Quality on SHP465 Mixed Amphetamine Salts Extended-Release Treatment Response in Adults with Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

Sleep problems are common in adults with attention-deficit/hyperactivity disorder (ADHD). The presence of sleep problems at the time of presentation for ADHD treatment could impact the level of improvement in ADHD symptoms or executive function occurring with ADHD pharmacotherapy. Therefore, we examined the influence of baseline sleep quality on the effects of SHP465 mixed amphetamine salts (MAS) extended-release.

METHODS

Adults (18-55 years) with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision-defined ADHD and baseline ADHD Rating Scale IV (ADHD-RS-IV) total scores ≥ 24 were randomized to once-daily SHP465 MAS (12.5-75 mg) or placebo in a 7-week, double-blind, dose-optimization study. Post-hoc analyses evaluated SHP465 MAS treatment effects on ADHD symptoms, using the ADHD-RS-IV, and executive function, using the Brown Attention-Deficit Disorder Scale (BADDS), based on baseline sleep quality as defined by Pittsburgh Sleep Quality Index (PSQI) scores [sleep quality impaired (PSQI total score > 5; PSQI component scores 2 or 3) versus not impaired (PSQI total score ≤ 5; PSQI component scores 0 or 1)]. Analyses were conducted in the intent-to-treat population.

RESULTS

Of 280 enrolled participants, 272 were randomized (placebo, n = 135; SHP465 MAS, n = 137). The intent-to-treat population consisted of 268 participants (placebo, n = 132; SHP465 MAS, n = 136), and 170 participants (placebo, n = 76; SHP465 MAS, n = 94) completed the study. Treatment differences nominally favored SHP465 MAS over placebo in both sleep impairment groups regarding ADHD-RS-IV total score changes (all nominal p < 0.05), except for those with impairment defined by sleep efficiency (p = 0.2696), and regarding BADDS total score changes (all nominal p < 0.05), except for those with impairment defined by sleep duration (p = 0.1332) and sleep efficiency (p = 0.8226). There were no statistically significant differences in SHP465 MAS treatment effects between sleep impairment groups.

CONCLUSIONS

Improvements in ADHD symptoms and executive function occurred with dose-optimized SHP465 MAS, regardless of baseline impairment in some aspects of sleep in adults with ADHD, with no significant differences observed as a function of sleep impairment.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov identifier-NCT00150579.

Seasonal variation of spontaneous blink rate and beta EEG activity

Seasonal variations of the photoperiod have been shown to regulate biological and behavioral functions, with also effects on clinical symptom and course of several psychiatric conditions. Although melatonin is considered the principal signal used to transmit informations about the light and dark cycle, a dopamine (DA) role in regulating seasonal changes has been suggested. Few studies have addressed a seasonal pattern of dopamine, and human studies have been conducted on inter-subject differences, comparing measures obtained during fall-winter with those of spring-summer. We studied within-subject seasonal changes of blink rate (BR), a indirect marker of central DA activity, in 26 normal subjects (15 females and 11 males, mean age: 24.7 ± 4.0) during winter, spring, summer and fall. Occipital EEG activity and subjective measures of vigilance and mood were also assessed to account for variations on arousal and fatigue. A significant seasonal effect was found for BR, with higher rate in summer, and for EEG beta activity, with higher activity in spring and summer. Subjective fatigue was found higher in winter. According to our data, it is possible that higher BR and increased EEG beta activity result by an arousal activation sustained by dopamine systems during the months with a long photoperiod.

Neuropathological Developments in Sudden Infant Death Syndrome

A wide variety of neuropathological abnormalities have been investigated in infants who have died of sudden infant death syndrome (SIDS). Issues which detracted from early studies included failure to use uniform definitions of SIDS and lack of appropriately matched control populations. Development of the triple risk model focused attention on the concept of an inherent susceptibility to unexpected death in certain infants, with research demonstrating a role for the neurotransmitter serotonin within the brainstem. However, it now appears that neuropathological abnormalities in SIDS infants are more complex than a simple serotonergic deficiency in certain medullary nuclei but instead could involve failure of an integrated network of neurochemical transmitters in a variety of subcortical locations. The following overview examines recent research developments looking particularly at the potential role of the peptide neurotransmitter substance P and its neurokinin-1 receptor in multiple nuclei within the brainstem, asymmetry and microdysgenesis of the hippocampus, and decreased orexin levels within dorsomedial, perifornical, and lateral levels in the hypothalamus. Whether such research will lead to identifiable biomarker for infants at risk of SIDS is yet to be established. Use of standardized and consistent methods of classifying and categorizing infant deaths will be pivotal in generating reproducible research results.

The sleep network organization during slow-wave sleep is more stable with age and has small-world characteristics more marked than during REM sleep in healthy men

Sleep plays an important role in cognitive functioning. However, few studies have investigated the sleep network organization. The aim of our study was to empirically investigate the presence and the stability with age of a small-world network organization during REM and slow-wave sleep using the effective connectivity measured by the Granger causality. Polysomnographic data from 30 healthy men recruited prospectively were analysed. To obtain the 19 × 19 connectivity matrix of all possible pairwise combinations of electrodes by the Granger causality method from our EEG data, we used the Toolbox MVGC multivariate Granger causality. The computation of the network measures was realised by importing these connectivity matrices into the EEGNET Toolbox. Even if all small-world coefficients obtained are compatible with a small-world network organization during REM and slow-wave sleep, slow-wave sleep seems to have a small-world network organization more marked than REM sleep. Moreover, the sleep network organization is affected greater by age during REM sleep than during slow-wave sleep. In healthy individuals, the highlighting of a sleep network organization during slow-wave sleep more stable with age and with small-world characteristics more marked than during REM sleep may help to better understand the global and local processing of information during sleep.

Sleep and brain infections

Sleep is frequently altered in systemic infections as a component of sickness behavior in response to inflammation. Sleepiness in sickness behavior has been extensively investigated. Much less attention has instead been devoted to sleep and wake alterations in brain infections. Most of these, as other neuroinfections, are prevalent in sub-Saharan Africa. The present overview highlights the importance of this topic from both the clinical and pathogenetic points of view. Vigilance states and their regulation are first summarized, emphasizing that key nodes in this distributed brain system can be targeted by neuroinflammatory signaling. Sleep-wake changes in the parasitic disease human African trypanosomiasis (HAT) and its animal models are then reviewed and discussed. Experimental data have revealed that the suprachiasmatic nucleus, the master circadian pacemaker, and peptidergic cell populations of the lateral hypothalamus (the wake-promoting orexin neurons and the sleep-promoting melanin-concentrating hormone neurons) are targeted by African trypanosome infection. It is then discussed how prominent and disturbing are sleep changes in HIV/AIDS, also when the infection is cured with antiretroviral therapy. This recalls attention on the bidirectional interactions between sleep and immune system, including the specialized brain immune response of which microglial cells are protagonists. Sleep changes in an ancient viral disease, rabies, and in the emerging infection due to Zika virus which causes a congenital syndrome, are also dealt with. Altogether the findings indicate that sleep-wake regulation is targeted by brain infections caused by different pathogens and, although the relevant pathogenetic mechanisms largely remain to be clarified, these alterations differ from hypersomnia occurring in sickness behavior. Thus, brain infections point to the vulnerability of the neural network of sleep-wake regulation as a highly relevant clinical and basic science challenge.

Waking up too early - the consequences of preterm birth on sleep development

Good quality sleep of sufficient duration is vital for optimal physiological function and our health. Sleep deprivation is associated with impaired neurocognitive function and emotional control, and increases the risk for cardiometabolic diseases, obesity and cancer. Sleep develops during fetal life with the emergence of a recognisable pattern of sleep states in the preterm fetus associated with the development, maturation and connectivity within neural networks in the brain. Despite the physiological importance of sleep, surprisingly little is known about how sleep develops in individuals born preterm. Globally, an estimated 15 million babies are born preterm (<37 weeks gestation) each year, and these babies are at significant risk of neural injury and impaired brain development. This review discusses how sleep develops during fetal and neonatal life, how preterm birth impacts on sleep development to adulthood, and the factors which may contribute to impaired brain and sleep development, leading to altered neurocognitive, behavioural and motor capabilities in the infant and child. Going forward, the challenge is to identify specific risk factors for impaired sleep development in preterm babies to allow for the design of interventions that will improve the quality and quantity of sleep throughout life.

Effects of Cannabinoid Agonists and Antagonists on Sleep and Breathing in Sprague-Dawley Rats

Study Objectives

There are no pharmacological treatments for obstructive sleep apnea syndrome, but dronabinol showed promise in a small pilot study. In anesthetized rats, dronabinol attenuates reflex apnea via activation of cannabinoid (CB) receptors located on vagal afferents; an effect blocked by cannabinoid type 1 (CB1) and/or type 2 (CB2) receptor antagonists. Here, using a natural model of central sleep apnea, we examine the effects of dronabinol, alone and in combination with selective antagonists in conscious rats chronically instrumented to stage sleep and measure cessation of breathing.

Methods

Adult male Sprague-Dawley rats were anesthetized and implanted with bilateral stainless steel screws into the skull for electroencephalogram recording and bilateral wire electrodes into the nuchal muscles for electromyogram recording. Each animal was recorded by polysomnography on multiple occasions separated by at least 3 days. The study was a fully nested, repeated measures crossover design, such that each rat was recorded following each of 8 intraperitoneal injections: vehicle; vehicle and CB1 antagonist (AM 251); vehicle and CB2 antagonist (AM 630); vehicle and CB1/CB2 antagonist; dronabinol; dronabinol and CB1 antagonist; dronabinol and CB2 antagonist; and dronabinol and CB1/CB2 antagonist.

Results

Dronabinol decreased the percent time spent in rapid eye movement (REM) sleep. CB receptor antagonists did not reverse this effect. Dronabinol also decreased apneas during sleep, and this apnea suppression was reversed by CB1 or CB1/CB2 receptor antagonism.

Conclusions

Dronabinol's effects on apneas were dependent on CB1 receptor activation, while dronabinol's effects on REM sleep were CB receptor-independent.

Whole-Brain Mapping of Direct Inputs to and Axonal Projections from GABAergic Neurons in the Parafacial Zone

The GABAergic neurons in the parafacial zone (PZ) play an important role in sleep-wake regulation and have been identified as part of a sleep-promoting center in the brainstem, but the long-range connections mediating this function remain poorly characterized. Here, we performed whole-brain mapping of both the inputs and outputs of the GABAergic neurons in the PZ of the mouse brain. We used the modified rabies virus EnvA-ΔG-DsRed combined with a Cre/loxP gene-expression strategy to map the direct monosynaptic inputs to the GABAergic neurons in the PZ, and found that they receive inputs mainly from the hypothalamic area, zona incerta, and parasubthalamic nucleus in the hypothalamus; the substantia nigra, pars reticulata and deep mesencephalic nucleus in the midbrain; and the intermediate reticular nucleus and medial vestibular nucleus (parvocellular part) in the pons and medulla. We also mapped the axonal projections of the PZ GABAergic neurons with adeno-associated virus, and defined the reciprocal connections of the PZ GABAergic neurons with their input and output nuclei. The newly-found inputs and outputs of the PZ were also listed compared with the literature. This cell-type-specific neuronal whole-brain mapping of the PZ GABAergic neurons may reveal the circuits underlying various functions such as sleep-wake regulation.

The pharmacology of amphetamine and methylphenidate: Relevance to the neurobiology of attention-deficit/hyperactivity disorder and other psychiatric comorbidities

Psychostimulants, including amphetamines and methylphenidate, are first-line pharmacotherapies for individuals with attention-deficit/hyperactivity disorder (ADHD). This review aims to educate physicians regarding differences in pharmacology and mechanisms of action between amphetamine and methylphenidate, thus enhancing physician understanding of psychostimulants and their use in managing individuals with ADHD who may have comorbid psychiatric conditions. A systematic literature review of PubMed was conducted in April 2017, focusing on cellular- and brain system-level effects of amphetamine and methylphenidate. The primary pharmacologic effect of both amphetamine and methylphenidate is to increase central dopamine and norepinephrine activity, which impacts executive and attentional function. Amphetamine actions include dopamine and norepinephrine transporter inhibition, vesicular monoamine transporter 2 (VMAT-2) inhibition, and monoamine oxidase activity inhibition. Methylphenidate actions include dopamine and norepinephrine transporter inhibition, agonist activity at the serotonin type 1A receptor, and redistribution of the VMAT-2. There is also evidence for interactions with glutamate and opioid systems. Clinical implications of these actions in individuals with ADHD with comorbid depression, anxiety, substance use disorder, and sleep disturbances are discussed.

Deletion of Trace Amine-Associated Receptor 1 Attenuates Behavioral Responses to Caffeine

Trace amines (TAs), endogenous amino acid metabolites that are structurally similar to the biogenic amines, are endogenous ligands for trace amine-associated receptor 1 (TAAR1), a GPCR that modulates dopaminergic, serotonergic, and glutamatergic activity. Selective TAAR1 full and partial agonists exhibit similar pro-cognitive, antidepressant- and antipsychotic-like properties in rodents and non-human primates, suggesting TAAR1 as a novel target for the treatment of neurological and psychiatric disorders. We previously reported that TAAR1 partial agonists are wake-promoting in rats and mice, and that TAAR1 knockout (KO) and overexpressing mice exhibit altered sleep-wake and EEG spectral composition. Here, we report that locomotor and EEG spectral responses to the psychostimulants modafinil and caffeine are attenuated in TAAR1 KO mice. TAAR1 KO mice and WT littermates were instrumented for EEG and EMG recording and implanted with telemetry transmitters for monitoring locomotor activity (LMA) and core body temperature (T_b). Following recovery, mice were administered modafinil (25, 50, 100 mg/kg), caffeine (2.5, 10, 20 mg/kg) or vehicle p.o. at ZT6 in balanced order. In WT mice, both modafinil and caffeine dose-dependently increased LMA for up to 6 h following dosing, whereas only the highest dose of each drug increased LMA in KO mice, and did so for less time after dosing. This effect was particularly pronounced following caffeine, such that total LMA response was significantly attenuated in KO mice compared to WT at all doses of caffeine and did not differ from Vehicle treatment. T_b increased comparably in both genotypes in a dose-dependent manner. TAAR1 deletion was associated with reduced wake consolidation following both drugs, but total time in wakefulness did not differ between KO and WT mice. Furthermore, gamma band EEG activity following both modafinil and caffeine treatment was attenuated in TAAR1 KO compared to WT mice. Our results show that TAAR1 is a critical component of the behavioral and cortical arousal associated with two widely used psychostimulants with very different mechanisms of action. Together with our previous findings, these data suggest that TAAR1 is a previously unrecognized component of an endogenous wake-modulating system.

Sleep and hypothalamic pituitary adrenal axis responses to metyrapone in posttraumatic stress disorder

Disturbed sleep is a core feature of posttraumatic stress disorder (PTSD), characterized in part by decreased delta power sleep that may result from stress-related alterations in corticotropin releasing factor (CRF), hypothalamic pituitary adrenal axis (HPA) regulation and glucocorticoid signaling. Overnight HPA axis response mediating sleep disturbances in men and women with PTSD was examined using a metyrapone challenge. Metyrapone blocks cortisol synthesis, removing negative feedback, and increases the release of hypothalamic CRF and pituitary adrenocorticotropic hormone (ACTH). Laboratory-based polysomnography was used to monitor the sleep of 66 medically healthy, medication-free men and pre-menopausal follicular phase women including 33 with chronic PTSD (16 women and 17 men) and 33 age- and sex-matched controls (14 women and 19 men) over 3 consecutive nights. Participants completed an overnight metyrapone challenge after an adaptation and baseline night of sleep and ACTH was obtained by repeated blood sampling. Metyrapone resulted in a greater increase in ACTH and greater decreases in cortisol and delta spectral power sleep in PTSD subjects compared to controls, and a greater increase in ACTH in women compared to men. There was no sex difference in metyrapone effects on delta power sleep, and no significant metyrapone by PTSD by sex interactions with either ACTH or delta power sleep. Regression analyses indicated that a greater increase in ACTH response was associated with a greater decrease in delta power sleep response in PTSD subjects, but no such relationship was found in controls. The PTSD group difference was similar in men and women. These results suggest that stress-related alterations of the HPA axis in PTSD may contribute to sleep difficulties. Therapeutics that target the HPA axis may offer promise as a potential future treatment for PTSD and related sleep difficulties.

A Double-Blind, Placebo-Controlled, Phase II Study to Determine the Efficacy, Safety, Tolerability and Pharmacokinetics of a Controlled Release (CR) Formulation of Mazindol in Adults with DSM-5 Attention-Deficit/Hyperactivity Disorder (ADHD)

BACKGROUND

Mazindol is under investigation for the treatment of attention-deficit/hyperactivity disorder (ADHD) because of its alertness-enhancing properties. A novel controlled-release (CR) formulation of mazindol was developed to allow once-daily dosing.

OBJECTIVE

The aim of this study was to evaluate the efficacy of mazindol CR in adults with ADHD.

DESIGN

We conducted a randomized, double-blind, placebo-controlled 6-week trial.

METHODS

Subjects diagnosed with ADHD using the Mini-International Neuropsychiatric Structured Interview (MINI) and with an ADHD Rating Scale, Diagnostic and Statistical Manual of Mental Disorders 5th Edition (ADHD-RS-DSM5) score ≥ 28 were randomized to receive placebo or 1-3 mg/day of mazindol for 6 weeks. The primary endpoint was the reduction from baseline in the ADHD-RS-DSM5 score on Day 42. Secondary endpoints were response rates defined by change in ADHD-RS-DSM5 (≥ 30 or ≥ 50% reduction) and dichotomized Clinical Global Impression-Improvement (CGI-I) score (1 or 2). An exploratory endpoint of functional impairment, as measured by the Target Impairment Scale, examined individualized deficits in specific settings. Safety, tolerability, and pharmacokinetics were assessed.

RESULTS

Eighty-five participants were randomized (n = 43 active, 42 placebo); 75 completed. Weekly ADHD-RS-DSM5 measurements after mazindol differed from placebo beginning at Day 7, with a least squares mean difference (active-placebo) of - 13.2 at Day 42 and an effect size of 1.09. For the 30% or more reduction in ADHD-RS-DSM5 (minimal response), a significant difference (active-placebo) was seen starting at Day 7 and continuing to Day 42. For the CGI-I (1 or 2) and for the 50% or more reduction in ADHD-RS-DSM5 (measures of excellent response), the differences began at Day 14 and continued to Day 42. Functional impairment was significantly different in the proportion achieving at least a 50% reduction in target impairment score (42.9% mazindol vs 11.9% placebo) by Day 42. Dry mouth, nausea, fatigue, heart rate (HR) increased, decreased appetite, and constipation were more prevalent for mazindol versus placebo. Overall, mazindol CR had minimal effects on blood pressure and small effects on HR.

CONCLUSION

Mazindol CR was efficacious in the treatment of adults with ADHD, with a large effect size, and was well tolerated, supporting the progression to phase III. (Clinicaltrials.gov Registration No. NCT02808104).

In Search of a Good Night's Sleep

A good night's sleep is essential to overall physical, cognitive, and emotional well-being. Sleep deprivation, whether general or related to time changes (e.g., daylight saving time), contributes to decreased cognition, impaired memory, poor coordination, mood fluctuations, increased risk of heart disease and diabetes, and weight gain, among others. The sleep cycle is defined by five stages and two distinct parts-rapid eye movement (REM) and non-REM sleep-that work to promote not only the quantity of sleep but also the quality of sleep, which impacts overall health. Each stage of sleep is influenced by various neurochemical actions among the brain regions. The neurochemistry and neuropath-ways related to the sleep/wake cycle as well as the mechanisms of action of sleep-inducing and wake-promoting medications are explored. [Journal of Psychosocial Nursing and Mental Health Services, 55(10), 19-26.].

Mapping the Hypocretin/Orexin Neuronal System: An Unexpectedly Productive Journey

Early in 1998, we (de Lecea et al., 1998) and others (Sakurai et al., 1998) described the same hypothalamic neuropeptides, respectively called the hypocretins or orexins, which were discovered using two different approaches. In December of that year, we published the subject of this commentary in the Journal of Neuroscience: a highly detailed anatomical description of the extensive axonal projections of the hypocretin/orexin neurons. Although the function of this system was unknown at the time, a large body of literature today attests that the hypocretin/orexin neuropeptides play important roles in multiple physiological functions, particularly in sleep/wake regulation. Neuroanatomical studies are rarely frontline news, but the citation rate of this paper underscores the critical nature of such basic research. Based in part on this detailed description, the hypocretin/orexin neuropeptides have since been studied in many different areas of neuroscience research, including sleep/wake regulation, feeding, addiction, reward and motivation, anxiety and depression, cardiovascular regulation, pain, migraine, and neuroendocrine regulation, including reproduction. Thus, this paper has had a surprisingly broad impact on neuroscience research, particularly since it was originally rejected by the Journal!

Neuronal substrates of sleep homeostasis; lessons from flies, rats and mice

Sleep homeostasis is a fundamental property of vigilance state regulation that is highly conserved across species. Neuronal systems and circuits that underlie sleep homeostasis are not well understood. In Drosophila, a neuronal circuit involving neurons in the ellipsoid body and in the dorsal Fan-shaped body is a candidate for both tracing sleep need during waking and translating it to increased sleep drive and expression. Sleep homeostasis in rats and mice involves multiple neuromodulators acting on multiple wake- and sleep-promoting neuronal systems. A functional central homeostat emerges from A₁ receptor mediated actions of adenosine on wake-promoting neurons in the basal forebrain and hypothalamus, and A_2A adenosine receptor-mediated actions on sleep-promoting neurons in the preoptic hypothalamus and nucleus accumbens.