Sleep Disorders Medicine Research Articles

Reflections on a journey as sleep researcher and geriatric psychiatrist.

After first recalling the origins of my interest in sleep and dreams at UVa (1969) and my MD thesis at Yale on sleep in mood disorders (1973), I will describe my service to the field of sleep disorders medicine, through various roles in the American Sleep Disorders Association, the Institute of Medicine, the National Institute of Mental Health, and the DSM-5 Task Force of the American Psychiatric Association. I will then present the broad themes of my contributions to psychiatric sleep research, focusing on the neurobiology of sleep as a dimension of the risk and protective architecture for depression in older adults, as a bridge to diagnostic and treatment issues in later-life depression, and to clinical and translational neuroscience addressing the intersections of sleep, aging, and mind/brain health. Throughout this narrative, I highlight many relationships with mentors and mentees. All of my scientific activity has been team-based, providing the social matrix for the physician-scientist I have become. This paper is part of the Living Legends in Sleep Research series, which is sponsored by Idorsia Pharmaceuticals and Jazz Pharmaceuticals.

Sleep Disorders Medicine: Basic Science, Technical Considerations, and Clinical Aspects

Sleep Disorders Medicine: Basic Science, Technical Considerations, and Clinical Aspects

Neurobiologic Mechanisms of Sleep and Wakefulness

Neurobiologic Mechanisms of Sleep and Wakefulness

Short Duration of Sleep Is Associated with Hyperleptinemia in Taiwanese Adults

Higher plasma levels of leptin have been associated with increased cardiometabolic risk. The aim of this study was to investigate the association between short duration of sleep and hyperleptinemia in Taiwanese adults. We examined the association between duration of sleep and hyperleptinemia in 254 men and women recruited from the physical examination center at a regional hospital in southern Taiwan. Hyperleptinemia was defined as a plasma leptin level of 8.13 ng/mL and above. Short sleep duration was defined as < 6.5 h/day. Multiple logistic regression analysis was used to assess the association between short duration of sleep and hyperleptinemia. In females, short duration of sleep (< 6.5 h/day; OR = 2.15, 95% CI = 0.99-4.78), greater hip circumference (OR = 3.00, CI = 1.13-8.78), higher percent body fat (OR = 1.75, CI = 1.07-2.95), and higher white blood cell counts (OR = 1.67, CI = 1.26-2.28) were associated with an increased risk of hyperleptinemia. In males, greater body weight was significantly associated with an increased risk of hyperleptinemia (OR = 3.55, 95% CI = 1.46-10.23). There was also a trend of association (p = 0.096) between short duration of sleep and an increased risk of hyperleptinemia (OR = 4.98, 95% CI = 0.80-42.40). In this study of healthy Taiwanese adults, short duration of sleep was significantly associated with hyperleptinemia in women, and the association was independent of adiposity.

Behavioral Sleep Medicine

Behavioral Sleep Medicine

Rebuttal From Dr Simon

I find myself in agreement with many of the points made by my colleagues on the “Pro” side of this discussion.1Fleishman SA Collop NA Aronsky AJ McCann KM Point: should board certification be required for sleep test interpretation? Yes.Chest. 2013; 144: 9-11Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar I agree that board-certified sleep medicine physicians (BCSMPs) possess the training and competence in sleep medicine to provide reliable interpretation of diagnostic tests, but I do not agree that this competence is unique to BCSMPs. For example, the performance of polysomnography (PSG) and PSG interpretation is a core competency in neurology fellowships.2American Board of Psychiatry & Neurology Psychiatry and Neurology Core Competencies Version 4.1. American Board of Psychiatry & Neurology website.http://www.abpn.com/downloads/core_comp_outlines/core_psych_neuro_v4.1.pdfGoogle Scholar And as we have demonstrated with the Walla Walla Project, referred to in my “Con” argument,3Simon Jr, RD Counterpoint: should board certification be required for sleep test interpretation?.No. Chest. 2013; 144: 11-13Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar others can be trained to successfully interpret sleep studies. Why should these trained physicians be denied the ability to read sleep studies? My fundamental utilitarian argument is that the number of patients with significant sleep disorders vastly exceeds the capacity of our medical system to care for them if only BCSMPs are permitted to read studies and care for such patients. My colleagues from the American Academy of Sleep Medicine (AASM) do not address this issue in their statement. They do bring up an argument that BCSMP consultation prior to PSG improves CPAP usage by 58 min a night in a cohort study,4Pamidi S Knutson KL Ghods F Mokhlesi B The impact of sleep consultation prior to a diagnostic polysomnogram on continuous positive airway pressure adherence.Chest. 2012; 141: 51-57Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar but they do not address the fact that if consultations were required, the cohort that did not undergo consultation would likely have received no care for their OSA. A recent study from Australia suggests that OSA can be effectively managed in primary care with similar outcomes to those obtained in formal sleep centers.5Chai-Coetzer CL Antic NA Rowland LS et al.Primary care vs specialist sleep center management of obstructive sleep apnea and daytime sleepiness and quality of life: a randomized trial.JAMA. 2013; 309: 997-1004Crossref PubMed Scopus (143) Google Scholar I find myself in absolute agreement that formal education in sleep physiology and sleep disorders medicine is woefully inadequate in medical schools, residency programs, and fellowship programs.6Gamaldo CE Salas RE Sleep medicine education: are medical schools and residency programs napping on the job?.Nat Clin Pract Neurol. 2008; 4: 344-345Crossref PubMed Scopus (9) Google Scholar The AASM has worked to address this serious fault in academia,7Silber MH Academic sleep centers of the future: an achievable vision.Sleep. 2007; 30: 244-245PubMed Google Scholar but much more needs to be done both for health-care providers in training and health providers in practice. Humans spend 30% of their life sleeping; there are physiologic differences in nearly all systems between wake, non-rapid eye movement sleep, and rapid eye movement sleep, and there are serious sleep disorders that result in untold human suffering, disability, and premature death. It is absolutely unconscionable that extensive formal sleep physiology and sleep disorders medicine curricula are not an integral part of medical school training. A fundamental understanding of the physiology of sleep and of sleep-disorders medicine should be core competencies for all health-care providers. Rather that limiting the number of patients who have access to sleep-disorders medicine, which is what surely will happen if only BCSMPs can interpret sleep studies, it would seem to me that a better strategy would be to encourage health-care providers to obtain the knowledge that it takes to diagnose and treat patients with uncomplicated sleep disorders and to learn to refer those who either do not respond to therapy or who have complicated sleep studies to BCSMPs. Academic and clinical sleep centers should be cooperative in these efforts, and continued educational efforts should be supported by the American Academy of Sleep Medicine for health-care providers in training as well as those currently in practice so that the enormous number of patients with sleep disorders can be effectively diagnosed and treated.

Biomarkers and Heart Disease

This review will focus on the evaluation of biomarkers and surrogate endpoints in chronic disease risk with a focus on cardiovascular disease. It provides an example of how identification of relevant biomarkers might be useful in sleep research and clinical care. Much of this review is derived from work performed by the Institute of Medicine (IOM) Committee on Qualification of Biomarkers and Surrogate Endpoints in Chronic Disease (see footnote in the Acknowledgments). This discussion will review the committee charge, definitions of biomarkers and other endpoints, biomarker evaluation framework, case studies of representative biomarkers, recommendations, and conclusions.

ATLAS OF CLINICAL SLEEP MEDICINE

edited by Meir H. Kryger, 380 pp., Elsevier, 2010, $145 Dr. Kryger, editor of the definitive reference in sleep, Principles and Practice of Sleep Medicine , has succeeded in creating an atlas that provides “an intellectual as well as sensory appreciation of the science of sleep and the practice of sleep disorders medicine.” The text is a concise yet comprehensive …

Let's change the field

We need to change how we think about sleep function, mechanism, control, dysfunction, and treatment. That is the challenge that is put forward in this journal. The challenge applies to the fields of sleep research and clinical sleep medicine at all levels and disciplines. This journal is to be eclectic in scope and ambitious in goal, from basic to applied science, from microscope to macroscopic function, from nucleic acid to neuronal systems, from fetus to adult, and from primitive organisms to the highly evolved. The fields of sleep research and circadian biology have existed for many years; the field of modern clinical sleep medicine only 40 years or so. But how long did we know about sleep before we knew about REM and NREM (Aserinsky and Kleitman, 1953)? How long did we know that most of us slept at night before we knew about the suprachiasmatic nucleus, the circadian clock, and their mode of control (Rusak and Zucker, 1979; Rosenwasser, 1988)? How long did we know about narcolepsy before we knew about the DQB1*0602 genetic locus and about the orexin/hypocretin neurotransmitter system (Mignot et al., 1997; Nishino et al., 2000; Taheri et al., 2002)? How much did we know about neuroanatomy and neurophysiology before we started to unravel the interplay of central systems controlling sleep? How long did we know about obstructive sleep apnea before we recognized it as a common disorder with a simple effective treatment (Sullivan et al., 1981)? How long did we ascribe a psychodynamic dream interpretation to sleepwalking and sleep terrors before we learned to think of them as NREM disorders of arousal (Broughton, 1968)? How long did we treat narcoleptic patients as “lazy” before we recognized narcolepsy's genetic and neurophysiologic bases? How long did we unquestioningly treat all insomniacs with barbiturates before we learned about sleep hygiene, sleep phases, and restless legs? How long did we ignore the impact of sleep deprivation on daily function, learning, and mood are why are so many still doing just that? And how many aspects of sleep are we still thinking about incorrectly because we continue to accept the common wisdom without questioning it, and because we have failed to widen our horizons sufficiently? And how many patients are still being treated inadequately because of approaches that continue to be based on tradition rather than science? Scientific studies that lead to significant changes in the field are the most important, and the fields of sleep research, circadian biology, and sleep disorders medicine are ripe for such changes. Not all studies can be as suddenly game changing as the discovery of REM sleep, but they do not need to be to change the way we think, the way we direct future research, and the way we treat our patients. From careful thought comes new speculation, then postulation, and then hypothesis generation. But these are only of value if these hypotheses are then tested in well-designed studies. The challenge is simple. Do not just accept what has been taught without careful questioning. Do not just design studies that can be done, but design studies that need to be done. Do not just conduct these studies in the easiest ways, but do so in the ways most likely to assure useful, reliable, and confirmable outcomes. Let us change the field.

Role of History Taking and Questionnaires when Approaching Sleep Disorders

Role of History Taking and Questionnaires when Approaching Sleep Disorders Ho-Won Lee Department of Neurology, School of Medicine, Brain Science and Engineering Institute, Kyungpook National University Although sleep disorders medicine is a relatively young discipline, there has been a dramatic increase in knowledge about understanding of the diagnosis, pathophysiology, and treatment of sleep disorders in the past 20 years. It is now possible to objectively diagnose most sleep disorders and specific treatments can be instituted. However, despite advances in our understanding of sleep disorders, accurate diagnosis and treatment always requires a detailed understanding of the patient's sleep/wake cycle and medical history. This overview discusses the role of history taking and questionnaires in diagnosing sleep disorders, such as obstructive sleep apnea, restless leg syndrome, and narcolepsy, which are frequently confronted in primary care.

Evaluating, Diagnosing, and Treating Sleep Disorders

&lt;P&gt;We live 24 hours per day, yet we pay attention to only those hours during which we are awake. Nonetheless, the hours spent asleep may be as important to our quantity and quality of life as food. Little attention has been paid to the sleeping child, and sleep-related problems tend to present to the child healthcare practitioner only when the youngster’s sleep disturbs the parents’ sleep. Indeed, the sleepless child has received majority attention from the pediatric community, and sleeplessness has for years been relegated to the realm of only developmental and/or behavioral disorders. However, we have come a long way in the past 15 years in understanding that sleep in infants, children, and adolescents is much more than a purely developmental phenomenon. Equal importance has been given to neurophysiologic, ontogenetic, and other physiological aspects of sleep.&lt;/P&gt;&lt;h4&gt;ABOUT THE GUEST EDITOR&lt;/h4&gt;&lt;P&gt;Shephen H. Sheldon, DO, FAAP, is Professor of Pediatrics, Northwestern University, Feinberg School of Medicine, and Director of the Sleep Medicine Center of Children’s Memorial Hospital. He is active in the clinical practice of pediatric sleep medicine and is involved in pediatric sleep medical education and research.&lt;/P&gt;&lt;P&gt;Dr. Sheldon is a graduate of the Midwestern University’s Chicago College of Osteopathic Medicine and completed his residency in pediatrics at Rush-Presbyterian-St. Luke’s Medical Center, Chicago. He has also completed a visiting faculty fellowship in medical education at Southern Illinois University Medical School and a fellowship in Sleep Disorders Medicine at the University of Chicago. &lt;/P&gt;&lt;P&gt;He has served as a consultant to the U.S. Public Health Service (USPHS) as a facilitator during the organizing conference for education/training in primary care pediatrics and internal medicine and has served as a grant reviewer for the USPHS and the National Institutes of Health (NIH) in research in primary care pediatrics. He served on the Education Committee of the Ambulatory Pediatrics Association and participated in the task force for the development of the medical school core curriculum for pediatric clerkships. He has served as Chair of the Continuing Medical Education Committee, and is a member of the National Sleep Medicine Course Committee, Education Committee, and Fellowship Training Committee of the American Academy of Sleep Medicine. &lt;/P&gt;&lt;P&gt;Dr. Sheldon served on the Board of Directors of the American Academy of Sleep Medicine from 2000 to 2006 and as Secretary/Treasurer 2003 to 2006. He was Board Liaison to the Continuing Medical Education Committee, is ad hoc member of the Fellowship Training Committee, and functions as a Center Accreditation Site visitor. He has served on the Board of Directors of the American Sleep Medicine Foundation as its Secretary, and is past Chair of the Educational Research Advisory Board. He also serves as Associate Editor, &lt;cite&gt;Journal of Clinical Sleep Medicine&lt;/cite&gt;, serves on the Board of Directors of the American Insomnia Association, and is active in the American Academy of Pediatrics. Dr. Sheldon was appointed to the American Board of Pediatrics in 2005 as representative to the American Board of Medical Specialties Sleep Medicine Policy and Examination Committee, and is a Diplomate in Sleep Medicine of the American Board of Pediatrics. He has co-chaired the Task Force of Smoke Detectors and Arousals in Children for the Standards Advisory Committee of Underwriter’s Laboratories.&lt;/P&gt;&lt;P&gt;He is the author of &lt;cite&gt;Pediatric Differential Diagnosis&lt;/cite&gt;, &lt;cite&gt;Pediatric Sleep Medicine&lt;/cite&gt;, &lt;cite&gt;Evaluating Sleep in Infants and Children&lt;/cite&gt;, &lt;cite&gt;Atlas of Sleep Medicine in Infants and Children&lt;/cite&gt;, and the forthcoming &lt;cite&gt;Differential Diagnosis in Sleep Medicine&lt;/cite&gt;, and is Senior Editor of the textbook &lt;cite&gt;Principles and Practice of Pediatric Sleep Medicine&lt;/cite&gt;.&lt;/P&gt;

Long sleep duration: A risk to health or a marker of risk?

Long sleep duration: A risk to health or a marker of risk?

Clinician's Guide to Sleep Disorders

Article AbstractBecause this piece does not have an abstract, we have provided for your benefit the first 3 sentences of the full text.This excellent resource was written for ease of use for busy clinicians (including primary care physicians) with little formal education in sleep disorders medicine. The editors and authors seem to have accomplished this goal very well with a variety of features: chapters titled based on symptoms (not necessarily diagnoses); beginning chapters with tabulations of symptoms and diagnoses; and frequent use of tables as a rapid and easy way to display most of the important information also covered in the text. Illustrations are useful, especially those regarding electroencephalogram/polysomnography, schematics of apneas/hypopneas, and an illustration of a sleep log (whose background was rather dark).†‹

EEG Arousal Norms by Age

Brief arousals have been systematically scored during sleep for more than 20 years. Despite significant knowledge concerning the importance of arousals for the sleep process in normal subjects and patients, comprehensive age norms have not been published. Seventy-six normal subjects (40 men) without sleep apnea or periodic limb movements of sleep, aged 18 to 70 years, slept in the sleep laboratory for 1 or more nights. Sleep and arousal data were scored by the same scorer for the first night (comparable to clinical polysomnograms) and summarized by age decade. There were no statistically significant differences for sex or interaction of sex by age (p > .5 for both). The mean arousal index increased as a function of age. Newman-Keuls comparisons (.05) showed arousal index in the 18- to 20-year and 21- to 30-year age groups to be significantly less than the arousal index in the other 4 age groups. Arousal index in the 31-to 40-year and 41-to 50-year groups was significantly less than the arousal index in the older groups. The arousal index was significantly negatively correlated with total sleep time and all sleep stages (positive correlation with stage 1 and wake). Brief arousals are an integral component of the sleep process. They increase with other electroencephalographic markers as a function of age. They are highly correlated with traditional sleep-stage amounts and are related to major demographic variables. Age-related norms may make identification of pathologic arousal easier.

The MSLT and MWT Should Not Be Used for the Assessment of Workplace Safety

There is good evidence that the Multiple Sleep Latency Test (MSLT) and, to a lesser extent, the Maintenance of Wakefulness Test (MWT) are both reliable and valid measures of changes in sleep tendency in individuals exposed to sleep deprivation. The MSLT has been used extensively in both research and clinical settings for almost 30 years. It is only natural to wish to extend the use of these tests to other environments in which determination of alertness is essential. In research settings, group differences, often based upon large numbers of individuals, are identified at given levels of probability. However, in clinical practice, the focus is on the individual patient, and group information may be limited by individual variability. When one considers public safety, the focus shifts even more to include not only individuals, but also occupational groups, legislative bodies, employers, and unions. Even the most elegant test of alertness will be of no use in the face of work schedules that violate circadian adaptation or require chronic sleep deprivation or exempt themselves as too important or not subject to universal physiologic rules. A safe workplace requires the presence of specific items such as fire extinguishers and the absence of specific items such as fire arms and alcohol. Unfortunately, society has not accepted that sleepiness has no place in a safe workplace. Necessary evidence of such understanding would include consistent application of already published peer-reviewed empirical research to design work schedules and limit errors; provision of approved areas for naps (the fire extinguisher for mild sleep deficits); provision of sleepiness counseling as a part of employee orientation, continuing education, safety, and health services; and design of the workplace to maximize employee alertness. Acceptance of the importance of sleepiness evaluations will require public and professional education similar to that common for the negative impact of alcohol. Education programs stressing poor productivity and increased medical costs associated with sleepiness need to be directed toward government and corporate entities so that they recognize that improving alertness would pay tremendous monetary dividends in addition to improved health and would lessen the need for workplace tests of alertness. Remarkably, and regrettably, many sleep medicine practitioners have not followed their clinical wisdom into their own sleep schedule and the work-sleep schedule of their students and employees and can also benefit from education. Development times for recognition, treatment, and sanctions for alcohol use and smoking have shown that behavior change in society is a slow process that takes many years. Acceptance of sleepiness as an equally important medical and social problem will require the concentrated effort of our entire field for an extended period. Society now accepts the value of tests of breath alcohol in and out of the workplace. Significant education remains until there is a similar acceptance of the negative consequences of sleepiness. Such acceptance presages evaluations of alertness aimed at the patient (employee) rather than the disease (required working conditions). When given the mandate to evaluate alertness, our research must provide a reliable, valid test and appropriate norms for the group to be examined. Acceptance of the MSLT or MWT as a valid measure of alertness in normals and then in patients would be important first steps. Unfortunately, recent work suggests that our understanding of the relationship between sleep and alertness is still at a relatively rudimentary level. Additional empirical work is needed to properly place tests of alertness within sleep disorders medicine. Obviously, even more understanding will be required to extrapolate those links to the workplace.

Sleep disorders: An overview

Although sleep disorders medicine is a relatively young discipline, understanding of the diagnosis, pathophysiology,and treatment of sleep disorders is evolving at a rapid pace. This overview discusses the history of the development of sleep disorders medicine, tracing changes in the diagnostic classification of sleep disorders as well as the role of polysomnography in diagnosis. This evolution is most evident for insomnia, one of the major sleep disturbances. The accumulation of epidemiologic data on the prevalence and temporal course of insomnia and emerging information regarding its pathophysiology derived from laboratory assessments have led to the development of new therapeutic approaches for primary insomnia and insomnia associated with medical and psychiatric disorders.

Paediatric sleep disorders: the need for multidisciplinary sleep clinics

The field of sleep disorders (SD) medicine crosses the boundaries of many medical specialties and disciplines. This paper aims to highlight the importance of a multidisciplinary approach to the assessment and treatment of SD in children, with particular reference to sleep-disordered breathing (SDB). The link between SDB and other SD (e.g. various parasomnias, sleep-related anxiety) illustrates the need for a holistic approach to assessment since these co-existing SD can be the most overt symptoms. Further, different approaches to treatment of the various SD are likely to be called for. Multidisciplinary care becomes particularly pertinent when dealing with clinical groups of children in which an increased prevalence of SD, including SDB, have been noted. Such groups include children with intellectual disabilities and those with neurological or psychiatric conditions. The nature of their basic condition may make it likely that SD will be overlooked with the daytime consequences of the nocturnal disturbance (e.g. cognitive/behavioural problems) misattributed to the underlying condition. Conclusion: An ideal national service would include a limited number of specialised sleep centres where a broad and multidisciplinary approach to the recognition, assessment and treatment of children’s SD was possible.

Paediatric sleep disorders: the need for multidisciplinary sleep clinics

The field of sleep disorders (SD) medicine crosses the boundaries of many medical specialties and disciplines. This paper aims to highlight the importance of a multidisciplinary approach to the assessment and treatment of SD in children, with particular reference to sleep-disordered breathing (SDB).The link between SDB and other SD (e.g. various parasomnias, sleep-related anxiety) illustrates the need for a holistic approach to assessment since these co-existing SD can be the most overt symptoms. Further, different approaches to treatment of the various SD are likely to be called for.Multidisciplinary care becomes particularly pertinent when dealing with clinical groups of children in which an increased prevalence of SD, including SDB, have been noted. Such groups include children with intellectual disabilities and those with neurological or psychiatric conditions. The nature of their basic condition may make it likely that SD will be overlooked with the daytime consequences of the nocturnal disturbance (e.g. cognitive/behavioural problems) misattributed to the underlying condition.Conclusion: An ideal national service would include a limited number of specialised sleep centres where a broad and multidisciplinary approach to the recognition, assessment and treatment of children's SD was possible.

The role of chronobiology in sleep disorders medicine.

This review is concerned with circadian (approximately 24 h) aspects of chronobiology, and how they relate to sleep disorders medicine. We begin with an introduction to the key concepts and paradigms of circadian rhythms research in general, including a description of homeostatic and circadian determinants of sleep timing. This is followed by a brief history of chronobiology in relation to sleep disorders medicine. Both animal and human circadian rhythm studies are considered. We trace historical changes in the relative emphasis placed on social contacts, light, and melatonin in human circadian rhythms research. Special attention is given to free-running, forced desynchrony, and ultra-short sleep/wake cycle findings of particular relevance to sleep disorders medicine. The latter part of the review comprises a description of the circadian rhythm sleep disorders, highlighting insights derived from basic circadian rhythms research, including recent advances in molecular genetics. We conclude that the role of chronobiology in sleep disorders medicine is profound and pervasive, and that the two disciplines will move ever closer as a natural function of important new insights into sleep and sleep disorders provided by basic circadian rhythms research.

To breathe, perchance to sleep: sleep-disordered breathing and chronic insomnia among trauma survivors.

Standard psychiatric classification (DSM-IV-TR) traditionally attributes post-traumatic sleep disturbance to a secondary or symptomatic feature of a primary psychiatric disorder. The DSM-IV-TR paradigm, however, has not been validated with objective sleep assessment technology, incorporated nosological constructs from the field of sleep disorders medicine, or adequately addressed the potential for post-traumatic stress disorder (PTSD) sleep problems to manifest as primary, physical disorders, requiring independent medical assessments and therapies. This paradigm may limit understanding of sleep problems in PTSD by promulgating such terms as "insomnia related to another mental disorder," a.k.a. "psychiatric insomnia." Emerging evidence invites a broader comorbidity perspective, based on recent findings that post-traumatic sleep disturbance frequently manifests with the combination of insomnia and a higher-than-expected prevalence of sleep-disordered breathing (SDB). In this model of complex sleep disturbance, the underlying sleep pathophysiology interacts with PTSD and related psychiatric distress; and this relationship appears very important as demonstrated by improvement in insomnia, nightmares, and post-traumatic stress with successful SDB treatment, independent of psychiatric interventions. Continuous positive airway pressure treatment in PTSD patients with SDB reduced electroencephalographic arousals and sleep fragmentation, which are usually attributed to central nervous system or psychophysiological processes. Related findings and clinical experience suggest that other types of chronic insomnia may also be related to SDB. We hypothesize that an arousal-based mechanism, perhaps initiated by post-traumatic stress and/or chronic insomnia, may promote the development of SDB in a trauma survivor and perhaps other patients with chronic insomnia. We discuss potential neurohormonal pathways and neuroanatomatical sites that may be involved in this proposed interaction between insomnia and SDB.