Reviews for Primary Care - Fall 2007 - (Page 41) Insomnia and Neurological Disorders Suprachiasmatic nucleus Sun/ambient light exposure Lens Pineal gland Retinohypothalamic tract Retina-Macula SCN INTRINSIC: Cataracts INTRINSIC: Macular degeneration EXTRINSIC: Excessive noise, inappropriate light exposure INTRINSIC: Decreased melatonin level EXTRINSIC: Decreased light exposure INTRINSIC: Underlying sleep disorders: obstructive sleep apnea, restless legs syndrome, periodic limb movement disorder, and psychiatric disorders Figure 1. Pathophysiology of sleep disruption in patients with dementia: potential environmental and intrinsic factors. SCN, suprachiasmatic nucleus. Modified from Figure 2 in Avidan A. Sleep in dementia and other neurodegenerative disorders. In: Culebras A, ed. Sleep Disorders and Neurologic Diseases, 2nd ed. New York: Taylor & Francis Group; submitted for publication. living quarters are examples of the indirect (external) mechanisms disturbing sleep (Figure 1). The new International Classification of Sleep Disorders (2nd edition)3 includes general diagnostic criteria for insomnia: (I) a complaint of difficulty initiating sleep, difficulty maintaining sleep, or early morning awakening or sleep that is chronically nonrestorative or is poor in quality; (II) the sleep difficulty occurs despite adequate opportunity and circumstances for sleep; (III) at least one of the following forms of daytime impairment related to the nighttime sleep difficulties is reported by the patient: (1) fatigue or malaise; (2) attention, concentration, or memory impairment; (3) social or vocational dysfunction or poor school performance; (4) mood disturbance or irritability; (5) daytime sleepiness; (6) motivation, energy, or initiative reduction; (7) proneness for errors or accidents at work or while driving; (8) tension headaches or gastrointestinal symptoms in response to sleep loss; and (9) concerns or worries about sleep.3 Classifying insomnia, however, has been challenging because of potential comorbidities and subtypes. The insomnia can be a primary complaint or can be secondary, or more appropriately, comorbid with another primary medical illness, psychiatric disorders, or other sleep disorders.3,4 Classifying insomnia by the duration of symptoms presents significant challenges because definition according to time does not provide any information about the etiology of the sleep disturbance or adequately describe patients who experience recurrent episodes of insomnia. Untreated insomnia can cause an insufficient amount of sleep and poor sleep, resulting in hypersomnolence, irritability, disruption in concentration, and depression, sometimes mistaken for dementia.1,5 In patients with underlying neurological disorders, sleep disturbances may also increase the risk of injury, compromise the quality of life, and create social and economic burdens for caregivers. Table 1 classifies sleep disorders in neurodegenerative disorders according to abnormal cellular aggregates. Patients with dementia are affected by a variety of underlying sleep disturbances, including insomnia, hypersomnia, circadian rhythm disturbances, excessive motor activity at night, nocturnal agitation, and wandering and abnormal nocturnal behaviors.2 Increased irritability, impaired motor and cognitive skills, depression, and fatigue are also common.1 Patients with dementia are at Table 1 Sleep Disorders in Neurodegenerative Disorders Tauopathies • Alzheimer’s disease Synucleinopathies • Parkinson’s disease • Diffuse Lewy body dementia • Multiple system atrophy Circadian rhythm disturbances (sundowning) Sleep-disordered breathing Hypersomnolence Sleep-disordered breathing Parasomnias: REM-sleep behavior disorder REM, rapid eye movement. VOL. 1 NO. 1 2007 REVIEWS FOR PRIMARY CARE 41
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