Elfairoz Yasser, Lama Ayache, Hania El Khayat, Bashar Qatanany, Amir Sharafkhaneh, K S Jagannatha Rao, Mohammad Nami
{"title":"Sleep and memory consolidation: Neural and cognitive perspectives.","authors":"Elfairoz Yasser, Lama Ayache, Hania El Khayat, Bashar Qatanany, Amir Sharafkhaneh, K S Jagannatha Rao, Mohammad Nami","doi":"10.1016/bs.pbr.2026.07.001","DOIUrl":"10.1016/bs.pbr.2026.07.001","url":null,"abstract":"<p><p>This chapter synthesizes current evidence on the role of sleep in memory consolidation, emphasizing the interplay between neural oscillations, synaptic plasticity, and cognitive processes. Sleep is conceptualized as an active state, facilitating the encoding, stabilization, and integration of memories into long-term storage. Distinct contributions of sleep stages are highlighted, with slow-wave sleep (SWS) supporting declarative memory consolidation through hippocampal-neocortical replay mechanisms, and Rapid eye movement (REM) sleep enhancing procedural and emotional memory processing. The synaptic homeostasis hypothesis is discussed as a central theoretical framework, proposing that sleep downscales synaptic strength while preserving salient memory traces, thereby optimizing neural efficiency and learning capacity. The chapter further explores the role of sleep spindles, delta oscillations, and high-frequency activity in mediating synaptic plasticity and memory reorganization. Neuroimaging evidence demonstrates coordinated activity between hippocampal and cortical networks during sleep, reinforcing the concept of memory replay and systems consolidation. Clinical implications are addressed, including the impact of sleep deprivation on cognitive performance and the potential for sleep-based interventions to enhance learning and mitigate cognitive decline. The chapter concludes by emphasizing the bidirectional relationship between sleep and memory, underscoring the importance of sleep quality in maintaining cognitive health across the lifespan.</p>","PeriodicalId":20598,"journal":{"name":"Progress in brain research","volume":"299 ","pages":"137-176"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148670671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Neurobiology of sleep apnea and cognitive impairment.","authors":"Amir Sharafkhaneh, Ahmed BaHammam","doi":"10.1016/bs.pbr.2026.07.008","DOIUrl":"10.1016/bs.pbr.2026.07.008","url":null,"abstract":"<p><p>Obstructive sleep apnea (OSA) has a broad and clinically important effect on cognition, most often impairing attention, executive function, memory, processing speed, and visuospatial ability, while language and immediate recall are relatively preserved. A substantial proportion of adults referred to sleep clinics already meet criteria for mild cognitive impairment at initial evaluation, particularly in moderate-to-severe OSA. This cognitive burden reflects multiple interacting mechanisms. Intermittent hypoxia promotes oxidative stress, mitochondrial dysfunction, and hippocampal injury through recurrent ischemia-reperfusion cycles. Sleep fragmentation disrupts slow-wave and REM sleep, impairing memory consolidation and glymphatic clearance. Neuroinflammation, endothelial dysfunction, and structural brain changes, including hippocampal atrophy, white matter hyperintensities, and reduced frontoparietal connectivity, may further compound injury over time. REM-related hypoxemia appears especially important for cerebrovascular injury and memory impairment. Measures such as hypoxic burden and oxygen desaturation indices may better capture brain risk than the apnea-hypopnea index alone. Older age, APOE ε4 genotype, obesity, hypertension, diabetes, depression, and prior cerebrovascular disease increase vulnerability and should guide screening and treatment priorities. Cognitive assessment in OSA should be domain-sensitive rather than based only on a single global cutoff. Effective therapy, especially positive airway pressure with adequate REM-period coverage, can improve alertness and selected cognitive outcomes, although attention may remain impaired despite improved oxygenation. In children, OSA can disrupt memory consolidation and working memory, and adenotonsillectomy often leads to only partial cognitive recovery. Cognition should therefore be considered a primary treatment outcome in both clinical care and future research.</p>","PeriodicalId":20598,"journal":{"name":"Progress in brain research","volume":"300 ","pages":"65-91"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148913013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jayanth Ks Rao, Amir Sharafkhaneh, Mohammad Nami, K S Jagannatha Rao
{"title":"Future horizons: Toward an integrated neuroscience of sleep.","authors":"Jayanth Ks Rao, Amir Sharafkhaneh, Mohammad Nami, K S Jagannatha Rao","doi":"10.1016/bs.pbr.2026.08.002","DOIUrl":"10.1016/bs.pbr.2026.08.002","url":null,"abstract":"<p><p>Sleep is now recognized as a vital biological process with roles beyond rest, including neurodevelopment, memory, emotional regulation, metabolism, immune function, and neuroprotection. Advances in neuroscience and technology reveal that sleep is an active, multifaceted process involving multiple brain and body systems. This chapter explores how neural networks, waste clearance, circadian rhythms, immune responses, and cognition interact to influence brain health and disease. We examine sleep's connections to neurodegeneration, mental illness, aging, and cognitive resilience. We also highlight emerging directions, including personalized sleep medicine, digital mapping of sleep networks, AI-based diagnostics, sleep biomarkers, novel therapies, wearable technologies, and circadian interventions. Integrating genetics, computational modelling, and real-time monitoring could transform both basic and clinical sleep science. Ultimately, advancing sleep neuroscience will require a unified approach that links molecular mechanisms to behavior and disease, positioning sleep as a central target for enhancing cognition, preventing brain disorders, supporting mental health, and promoting overall well-being.</p>","PeriodicalId":20598,"journal":{"name":"Progress in brain research","volume":"301 ","pages":"207-219"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148991071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nazia Uzma, Maryam Wajdi, Aasea Alhashmi, Bashar Qatanany, Amir Sharafkhaneh, Jagannatha Rao Kosagisharaf, Mohammad Nami
{"title":"REM sleep behavior disorder and synucleinopathies.","authors":"Nazia Uzma, Maryam Wajdi, Aasea Alhashmi, Bashar Qatanany, Amir Sharafkhaneh, Jagannatha Rao Kosagisharaf, Mohammad Nami","doi":"10.1016/bs.pbr.2026.07.009","DOIUrl":"10.1016/bs.pbr.2026.07.009","url":null,"abstract":"<p><p>Rapid Eye Movement (REM) Sleep Behavior Disorder (RBD) is a somnipathy characterized by a physiological failure of skeletal muscle atonia during REM sleep. Such a brainstem pathway disruption, which directly affects the pontomedullary reticular formation, disrupts the descending inhibitory pathways that normally cause muscle paralysis. Patients then are much more likely to act out their dreams and will have complex, often violent dream-enactment behaviors that may cause injury and disrupt sleep continuity. Almost two decades of research have shown that RBD is potentially a crucial early indicator for synucleinopathies (brain diseases that are related to the accumulation of alpha-synuclein protein). These diseases include Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Emerging biomarkers, neuroimaging results, and fluid-based biomarkers are discussed in the context of risk stratification and prediction of phenotypic pathophysiological transformation to overt neurodegenerative disease. Moreover, the chapter discusses how RBD provides a window for testing neuroprotective and disease-modifying therapies that may delay or prevent overt synucleinopathy. It also reviews current symptom management approaches that mix pharmacological treatment with non-pharmacological safety measures for injury prevention and neuromodulation technologies that target disrupted motor circuitry. Understanding the relationship between RBD and synucleinopathies offers a unique window into the earliest stages of neurodegeneration and presents new possibilities for early diagnosis, targeted treatment, and better patient outcomes.</p>","PeriodicalId":20598,"journal":{"name":"Progress in brain research","volume":"300 ","pages":"93-127"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148913144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mukul Jain, Nil Patil, Rupal Dhariwal, Mohammad Nami
{"title":"Neural correlates of insomnia and hyperarousal.","authors":"Mukul Jain, Nil Patil, Rupal Dhariwal, Mohammad Nami","doi":"10.1016/bs.pbr.2026.07.015","DOIUrl":"10.1016/bs.pbr.2026.07.015","url":null,"abstract":"<p><p>This chapter provides an exhaustive review of the neural substrates associated with insomnia and hyperarousal, considering the chronic disturbance of sleep from the complex perspective of a reciprocal biopsychosocial model. It focuses on several critical abnormalities observed on the structure and function of neuroanatomy, especially the hypersensitive reaction of the amygdala and insular cortex along with reduced reactivity of the prefrontal cortex that results in the development of emotional dysregulation and a continuous feeling of danger. At the circuitry level, it is possible to observe a substantial disturbance of the DMN and ECN connectivity. From a neurochemical point of view, this chapter describes the impact of the imbalances of GABA, serotonergic and noradrenergic systems in specific nuclei, such as the locus coeruleus and the tuberomammillary nucleus, together with HPA-axis overactivation and elevated cortisol levels that cause systemic cortical hyperarousal. As far as electrophysiological markers are concerned, there is a specific increase of beta wave activity in the waking resting-state as well as a decrease of restorative SWS and REM sleep stability. Lastly, this chapter gives some information about clinical relevance, especially about CBT-I, new neuromodulation strategies and brain-region specific pharmacotherapeutic options.</p>","PeriodicalId":20598,"journal":{"name":"Progress in brain research","volume":"301 ","pages":"1-35"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148991108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Insomnia phenotypes and neurocognitive biomarkers.","authors":"Mansoor Ahmed, Fawad Taj, Mohammad Nami","doi":"10.1016/bs.pbr.2026.07.010","DOIUrl":"10.1016/bs.pbr.2026.07.010","url":null,"abstract":"<p><p>Insomnia is increasingly understood as a heterogeneous disturbance of sleep-wake regulation shaped by interacting cognitive, physiological, circadian, neurobiological, and perceptual mechanisms. This chapter develops a phenotype-informed framework for insomnia that distinguishes descriptive clinical presentations from underlying mechanistic dimensions and measurable biomarker domains. Core phenotypes reviewed include cognitive-emotional hyperarousal, objective short sleep duration, paradoxical insomnia and sleep-state misperception, circadian misalignment, autonomic dysregulation, sleep-depth instability, psychiatric comorbidity, and night-to-night sleep variability. Particular attention is given to neurocognitive biomarkers, including attention, executive function, working memory, episodic memory, cognitive variability, and subjective cognitive burden, with emphasis on how outcomes differ across insomnia phenotypes. It also examines electrophysiological and sleep microstructure markers, including high-frequency EEG activity, slow-wave activity, spindles, microarousals, cyclic alternating pattern, cardiopulmonary coupling, and Odds Ratio Product as emerging indicators of sleep depth and state instability. Autonomic, circadian, physiological, neuroimaging, wearable, and AI-enabled multimodal approaches are evaluated for their potential to refine mechanistic understanding and support future precision sleep medicine. Across domains, the chapter emphasizes that no single biomarker currently provides sufficient specificity for diagnosis or treatment selection. Instead, insomnia phenotyping is most useful as an integrative, mechanism-informed approach that can improve clinical formulation, guide individualized treatment emphasis, and identify future research priorities.</p>","PeriodicalId":20598,"journal":{"name":"Progress in brain research","volume":"300 ","pages":"129-219"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148913026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Neuroscience and biomarkers of sleep in preterm and term infants: From state organization to clinical translation.","authors":"Nada Abouseif, Efthymios Papatzikis","doi":"10.1016/bs.pbr.2026.08.001","DOIUrl":"10.1016/bs.pbr.2026.08.001","url":null,"abstract":"<p><p>Infant sleep, viewed across the preterm-to-term continuum, is best understood not as a behavioral backdrop but as a developing neurobiological control system whose state organization offers a clinically accessible window onto central nervous system maturation. In this chapter we synthesize evidence on sleep across three contexts - the NICU, the post-discharge period, and community samples - and across three nested levels of organization: macro-architectural cycling between active, quiet, and indeterminate sleep; microstructural EEG features such as spindles, slow oscillations, and graphoelements; and the gradual emergence of circadian timing. We argue that infant sleep functions simultaneously as a mediator of brain development, a moderator of early vulnerability, and a marker of neurodevelopmental risk - a triple role that justifies treating sleep assessment as a core component of neonatal care rather than a supplementary concern. Yet the path from biomarker to bedside is far from frictionless. We examine the strengths and inferential limits of polysomnography, conventional and amplitude-integrated EEG, behavioral state coding, actigraphy, and autonomic-cardiorespiratory metrics, and we develop a reliability-validity-specificity framework for evaluating candidate biomarkers against the moving baselines of maturation, medication, illness, and environment. Throughout, we flag where current evidence supports causal mechanism, where it is merely correlational, and where the direction of effect may be bidirectional. The chapter closes with a three-step clinician-researcher bridge - assess, contextualize, decide - designed to translate multimodal sleep data into age-corrected, context-aware clinical decisions. Sleep, properly read, is not a research curiosity. It is a routine instrument of neurodevelopmental care.</p>","PeriodicalId":20598,"journal":{"name":"Progress in brain research","volume":"301 ","pages":"93-206"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148991101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jayanth Ks Rao, Lakshmi Sowmya Emani, Sejali Padhi, Amir Sharafkhaneh, Mohammad Nami, K S Jagannatha Rao
{"title":"Sleep, emotional regulation, and limbic-cortical dynamics: From basic mechanisms to clinical translation.","authors":"Jayanth Ks Rao, Lakshmi Sowmya Emani, Sejali Padhi, Amir Sharafkhaneh, Mohammad Nami, K S Jagannatha Rao","doi":"10.1016/bs.pbr.2026.07.002","DOIUrl":"10.1016/bs.pbr.2026.07.002","url":null,"abstract":"<p><p>Sleep is an essential biological process regulating emotions and involving interactions between limbic and cortical systems. The amygdala, hippocampus, insula, and anterior cingulate cortex function as a bottom-up network for emotional processing, whereas prefrontal regions control the top-down aspect. Neurophysiological, neurochemical, and network modifications affect these circuits during sleep stages i.e. rapid eye movement (REM) and non-REM (NREM) phases. Sleep deprivation throws this balance out of synchrony, making emotional responsiveness increasingly pronounced and regulation more compromised, and can lead to, or aggravate, mental health disorders such as depression, anxiety, and PTSD. This chapter integrates fundamental neuroscience, system modelling, neuroimaging, and clinical insights into account of limbic and cortical brain circuitry in the context of sleep-induced emotional regulation.</p>","PeriodicalId":20598,"journal":{"name":"Progress in brain research","volume":"299 ","pages":"177-215"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148670656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Archana Anil Kumar, Elisa Carracedo Trasorras, Nour Haitham, Bashar Qatanany, Amir Sharafkhaneh, K S Jagannatha Rao, Mohammad Nami
{"title":"Brain oscillations and sleep microarchitecture: From EEG to fMRI.","authors":"Archana Anil Kumar, Elisa Carracedo Trasorras, Nour Haitham, Bashar Qatanany, Amir Sharafkhaneh, K S Jagannatha Rao, Mohammad Nami","doi":"10.1016/bs.pbr.2026.07.003","DOIUrl":"10.1016/bs.pbr.2026.07.003","url":null,"abstract":"<p><p>This chapter covers the role of brain oscillations in shaping the microarchitecture of sleep and their role in physiological and pathological states. Neural oscillations (delta to gamma frequencies) are fundamental to the structure of sleep stages and play a central role in cognitive and restorative processes of the human brain. This chapter discusses how different oscillatory signatures characterize non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, with slow waves dominating deep sleep and desynchronization in REM sleep. Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are complementary to investigate sleep dynamics. EEG offers high temporal resolution in terms of oscillatory activity, and fMRI provides a spatial mapping of the network. The convergence of these modalities has provided new insights into sleep spindles, slow oscillations, and their association with large functional connections. Also emphasized in the chapter are the quantitative EEG metrics and advances in signal processing and machine learning that can help identify sleep stages and pathological patterns. The disruption of oscillatory dynamics in sleep disorders and neurodegenerative conditions is also explored as oscillatory biomarkers can be used as diagnostic and prognostic tools. Overall, the chapter highlights the implications of oscillatory dynamics as a common framework to connect sleep physiology with cognitive function and clinical applications, highlighting the potential for multimodal neuroimaging.</p>","PeriodicalId":20598,"journal":{"name":"Progress in brain research","volume":"299 ","pages":"51-96"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148670645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Madhavi Salim, Bashar Qatanany, Amir Sharafkhaneh, K S Jagannatha Rao, Mohammad Nami
{"title":"Neural mechanisms and architecture of sleep.","authors":"Madhavi Salim, Bashar Qatanany, Amir Sharafkhaneh, K S Jagannatha Rao, Mohammad Nami","doi":"10.1016/bs.pbr.2026.07.006","DOIUrl":"10.1016/bs.pbr.2026.07.006","url":null,"abstract":"<p><p>This chapter explores the neural mechanisms and architectural organization of sleep, which is essential for memory consolidation, neural plasticity, metabolic homeostasis, and cognitive function. Sleep is regulated by an integrated system of homeostatic sleep pressure and circadian rhythms that is linked to distributed neural networks such as the hypothalamus, brainstem, thalamus, basal forebrain, and cerebral cortex. Control of sleep is mediated through the balance between sleep-promoting networks (e.g. ventrolateral preoptic nucleus and its GABAergic projections) and arousal-promoting (e.g. orexinergic, cholinergic, monoaminergic, and histaminergic networks). This chapter looks at sleep from the macro and micro points of view and emphasizes the distinct neurophysiological attributes and functions of NREM and REM sleep. We focus on slow-wave activity, sleep spindles, and thalamocortical oscillations as electrophysiological substrates for synaptic plasticity, memory consolidation, and large-scale network synchronization. Research in polysomnography, neuroimaging, computational neuroscience, and artificial intelligence has also shed light on the neural architecture of sleep and its role in cognition, emotional regulation, and brain health. All in all, sleep is discovered as an emergent property of integrated neural systems that has a fundamental role to play in neuropsychiatric, metabolic, and neurodegenerative disorders and further scope for translational and clinical sleep investigations.</p>","PeriodicalId":20598,"journal":{"name":"Progress in brain research","volume":"299 ","pages":"1-50"},"PeriodicalIF":0.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148670674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}