Postgraduate Education Corner CONTEMPORARY REVIEWS IN SLEEP MEDICINE CHEST 242 Postgraduate Education Corner E xcessive daytime sleepiness (EDS) of unknown cause (ie, absence of sleep deprivation, soporific drugs, psychiatric causes, or other sleep disorders) is the sine qua non feature of hypersomnia of central origin. 1-3 Narcolepsy and idiopathic hypersomnia (IH) are the most common disorders that fall under this classification. EDS severity can be quantified subjec- tively with validated scales (ie, the Epworth sleep- iness scale) and objectively using the multiple sleep latency test (MSLT) and the maintenance of wakeful- ness test. 4 Hypersomnia of Central Origin: Narcolepsy and Idiopathic Hypersomnia Diagnostic Criteria and Clinical Features: Narcolepsy Narcolepsy (with or without cataplexy) is the best characterized and most common clinical disorder falling under the classification of hypersomnia of cen- tral origin. 2 The estimated prevalence of narcolepsy with cataplexy in the United States is 0.02% to 0.18% of the population, whereas narcolepsy without cataplexy is estimated at approximately 0.02%. The underlying Sleep Medicine Pharmacotherapeutics Overview Today, Tomorrow, and the Future (Part 2: Hypersomnia, Parasomnia, and Movement Disorders) Seema Gulyani, PhD, NP; Rachel E. Salas, MD; and Charlene E. Gamaldo, MD Over the past 10 years, significant strides have been made in therapeutics for sleep disorders. In this second installment of a two-part review series, we discuss the current evidence surrounding the mechanisms of actions, indications, efficacy, and adverse side effects associated with the cur- rent over-the-counter and pharmacotherapeutics for hypersomnia, parasomnias, and movement dis- orders of sleep. CHEST 2013; 143(1):242–251 Abbreviations: BZD 5 benzodiazepine; EDS 5 excessive daytime sleepiness; FDA 5 US Food and Drug Administra- tion; GABA 5 g-aminobutyric acid; ICSD-2 5 International Classification of Sleep Disorders–Second Edition; IH 5 idio- pathic hypersomnia; MSLT 5 multiple sleep latency test; NREM 5 non-rapid eye movement; OSA 5 obstructive sleep apnea; PSG 5 polysomnography; PTSD 5 posttraumatic stress disorder; RBD 5 rapid eye movement sleep behavior dis- order; REM 5 rapid eye movement; RLS 5 restless legs syndrome; SOREMP 5 sleep-onset rapid eye movement period; SRED 5 sleep-related eating disorder; SSRI 5 selective serotonin uptake inhibitor; SXB 5 sodium oxybate; TCA 5 tricyclic antidepressant neurobiologic cause remains unknown; however, cur- rent findings suggest an interplay between genetic and environmental factors. Although a marked reduc- tion in the density of hypocretin neurons found in the hypothalamus has been linked with the manifestation of the symptoms, the exact cause or trigger of this reduction remains unknown. Presumably, individuals with an underlying genetic predisposition may develop narcolepsy as the result of undetermined environ- mental triggers and exposure (within a potential crit- ical vulnerability window) in a similar fashion to the presumed risks associated with the development of multiple sclerosis. Family studies have supported this theory by the fact that both genetic and nongenetic factors appear to play a role. Moreover, the tight associa- tion between narcolepsy with cataplexy and the human leukocyte antigen allele DQB1 ∗ 0602 also lends sup- port to the neurobiologic comparisons with multiple sclerosis. 5,6 Narcolepsy With Cataplexy: The two essential diag- nostic features of narcolepsy with cataplexy are (1) a chief complaint of EDS almost daily for at least 3 months and (2) a definite history of cataplexy, defined Downloaded From: http://journal.publications.chestnet.org/ on 10/29/2015