Sleep disorders

The development of multidisciplinary centers and the increasing availability of consultation in the overlapping borderland that sleep disorders medicine shares with many specialties are leading to accurate diagnoses and successful treatment for patients of physicians who are aware of the clinical situations in which polysomnography or sleep latency testing could be helpful. Specific disorders are discussed.     

Sleep disorders

Patients with sleep disorders present with a variety of complaints including excessive daytime sleepiness, daytime spells, inability to sleep, uncomfortable sensation in the extremities, and unusual night time behaviors. This article provides eight vignettes on patients with sleep disorders including narcolepsy, idiopathic hypersomnia, obstructive sleep apnea, restless legs syndrome, and rapid eye movement behavior disorder. The discussion provides data regarding the epidemiology, pathophysiology, and diagnostic approach for these conditions. The various treatment options for these sleep disorders are also identified.     

Sleep disorders

Many pharmacologic and nonpharmacologic strategies are available to treat sleep disorders successfully. Conventional stimulants and the new stimulant modafinil have roles to play in the management of narcolepsy and idiopathic hypersomnia. Knowledge of the properties and clinical effects of these drugs allows adequate doses of medications to be used with the goal of attaining as maximal alertness as possible. A range of dopaminergic agents is available to treat restless legs syndrome; other medications such as opiates, benzodiazepines, and anticonvulsants can also be used. Successful use of the dopaminergic agents depends on an understanding of the phenomena of augmentation, rebound, and tolerance. Arousal parasomnias can be treated with behavioral methods such as hypnosis and drug therapy. Clonazepam provides relief of the symptoms in most patients with REM sleep behavior disorder.     

Sleep disorders in childhood

Childhood sleep-wake disorders are common and associated with significant impairment of quality of life. The recent discovery of hypocretin deficiency as the pathophysiologic basis for narcolepsy-cataplexy is likely to spur the development of hypocretin analogs for definitive treatment [82,83]. The link between disrupted sleep and daytime learning and childhood inattention is a challenging area of mind-brain interaction in which further progress is likely, once methodologic issues have been sorted out. The recent recognition of genetic influences in the control of circadian rhythms also may spur the development of specific therapies for circadian rhythm disorders. In many ways, sleep medicine is benefiting from recent progress in the basic neurosciences, genetics, and technology.     

Sleep in eating disorders

Sleep research on eating disorders has addressed two major questions: (1) the effects of chronic starvation in anorexia nervosa and of rapidly fluctuating eating patterns in bulimia nervosa on the sleep regulating processes and (2) the search for a significant neurobiological relationship between eating disorders and major depression. At present, the latter question appears to be resolved, since most of the available evidences clearly underline the notion that eating disorders (such as anorexia and bulimia nervosa) and affective disorders are two distinct entities. Regarding the effects of starvation on sleep regulation, recent research in healthy humans and in animals demonstrates that such a condition results in a fragmentation of sleep and a reduction of slow wave sleep. Although several peptides are supposed to be involved in these regulatory processes (i.e. CCK, orexin, leptin), their mode of action is still poorly understood. In opposite to these experimentally induced sleep disturbances are the findings that the sleep patterns in eating disorder patients per se do not markedly differ from those in healthy subjects. However, when focusing on the so-called restricting anorexics, who maintain their chronic underweight by strictly dieting, the expected effects of malnutrition on sleep can be ascertained. Furthermore, at least partial weight restoration results in a 'deepening' of nocturnal sleep in the anorexic patients. However, our knowledge about the neurobiological systems (as well as their circadian pattern of activity) that transmit the effects of starvation and of weight restoration on sleep is still limited and should be extended to metabolic signals mediating sleep.     

Sleep in neurodegenerative disorders

Neurodegenerative disorders are a group of heterogeneous, progressive disorders of varying etiology that affect one or more systems. They occur predominantly at older age, during which the structure and amount of sleep undergo changes. Neurodegenerative processes cause structural changes of the sleep/wake generators in the brainstem which result in disorders such as daytime sleepiness, insomnia, sleep-related movement and breathing disturbances, and disorders of the circadian rhythms. Some sleep disorders manifest years before the onset of neurodegenerative disorders and may serve as predictors. Polysomnography shows sleep fragmentation, tonic or phasic movements of the extremities, alteration of respiratory muscles, reduced slow wave sleep, REM sleep absence or without muscle atonia, increased arousal or wake activity, epileptiform EEG activity, and changes in sleep-related breathing. Very frequently, REM sleep behaviour disorder is associated with neurodegenerative disorders. In this overview we present symptoms, pathophysiology, and polysomnographic findings of sleep disorders in prevalent neurodegenerative disorders.     

Sleep in neuropsychiatric disorders

Sleep disorders have been recognized for millennia as a common complication of medical and neurologic disease. Virtually all neuropsychiatric disorders carry with them the potential for disturbances of sleep. When such complications do exist, they are typically associated with decreased quality of life, increased morbidity, and, in some cases, increased mortality rates. The prevalence of major sleep disorders among neurologic patients is high, but the rate of detection and treatment is quite low. The major sleep-related problems in this population can be divided into six areas: insomnia, circadian rhythm (sleep-wake schedule) disorders, hypersomnia, sleep-related breathing disorders, motor disturbances in sleep, and parasomnias. In this brief review, general clinical principles, diagnostic assessment and management guidelines for each of these areas are considered and their specific manifestations in neuropsychiatric disorders identified.     

Sleep in psychiatric disorders

Altered sleep patterns are prominent in the majority of psychiatric disorders. This article examines the psychiatric disorders that are most often associated to sleep dysfunction as it is related in clinical practice and describes the polysomnographic findings. Patient's main complaints are related to difficulty in initiating and maintaining sleep (initial or middle insomnia, respectively) and poor quality of sleep. Early awakening or terminal insomnia is most described in the depressive conditions. Hypersomnia may be the main symptom in some depressive disorders, as seasonal depression, depression with atypical features or depressive episodes in bipolar disorder. Polysomnographic evaluation shows, in general, a significative reduction in the efficiency and total time of sleep, in detriment to the amount of slow wave sleep. The reduction of rapid eye movement (REM) sleep latency is mainly described for the depression, but has also been reported in other psychiatric disorders.     

Sleep disorders in children

In general, childhood sleep disturbances can be accurately clinically diagnosed by the primary care physician, neurologist, or psychiatrist. Careful characterization of the "spells," either by history or home videotaping, may be sufficient. Often, no laboratory studies are needed if the physician can recognize the sleep disturbance and clinically differentiate it from epilepsy or migraine. Although behavioral approaches or "tincture of time" often alleviates a great many sleep disturbances in children, psychopharmacologic therapy has a role in many and can be judiciously prescribed with safety and efficacy.