Classification of sleep disorders comprises systems for classifying medical disorders associated with sleep. Systems have changed, increasingly using technological discoveries to advance the understanding of sleep and recognition of sleep disorders.

Three systems of classification are in use worldwide: the International Classification of Diseases (ICD), the Diagnostic and Statistical Manual of Mental Disorders (DSM), and the International Classification of Sleep Disorders (ICSD). The ICD and DSM lump different disorders together, while the ICSD tends to split related disorders into multiple discrete categories. There has, over the last 60 years, occurred a slow confluence of the three systems of classification. The validity and reliability of various sleep disorders are yet to be proved and need further research within the ever-changing field of sleep medicine.

Classification systems

Systems for the classification of sleep disorders are used to classify medical disorders related to human sleep patterns. Three systems of classification are in use worldwide: the International Classification of Diseases (ICD) developed by the World Health Organization (WHO) and intended for use by general and more specialized practitioners, the Diagnostic and Statistical Manual of Mental Disorders (DSM) from the American Psychiatric Association (APA) for psychiatrists and general practitioners, and the International Classification of Sleep Disorders (ICSD), an advanced system cultured by the American Academy of Sleep Medicine (AASM) for sleep specialists. The ICD and DSM lump different disorders together, while the ICSD tends to split related disorders into multiple discrete categories. There has, over the last 60 years, occurred a slow confluence of the three major classification systems.

History

Milestones The first book on sleep was published in 1830 by Robert MacNish; it described sleeplessness, nightmares, sleepwalking and sleep-talking. Narcolepsy, hypnogogic hallucination, wakefulness and somnolence were mentioned by other authors of the nineteenth century. Westphal, in 1877, described first case of narcolepsy, the name coined later by Gelineu in 1880 in association with cataplexy. Lehermitte called it paroxysmal hypersomnia in 1930 to differentiate it from prolonged hypersomnia. Roger in 1932 coined the term parasomnia and classified hypersomnia, insomnia and parasomnia. Kleitman in 1939 recognized types of parasomnias as nightmares, night terrors, somniloquy (sleep-talking), somnambulism (sleepwalking), bruxism (grinding of teeth), jactatians, enuresis, delirium, nonepileptic convulsions and personality dissociation. Broughton in 1968 developed classification of the arousal disorders as confusional arousals: night terrors and sleep walking. Insomnias were classified as primary and secondary until 1970 when they were recognized as symptoms of other disorders. Sir William Osler in 1906 correlated snoring, obesity and somnolence (sleepiness) to Dicken's description of Joe. Charles Burwell in 1956 recognized obstructive sleep apnea as Pickwickian syndrome. Circadian rhythm sleep disorders were discovered in 1981 by Weitzman as delayed sleep phase syndrome in contrast to advanced sleep phase syndrome in 1979.

Evolution of classifications of sleep disorders Classification of sleep disorders, as developed in the 19th century, used primarily three categories: insomnia, hypersomnia and nightmare. In the 20th century, increasingly in the last half of it, technological discoveries led to rapid advances in the understanding of sleep and recognition of sleep disorders. Major sleep disorders were defined following the development of electroencephalography (EEG) in 1924 by Hans Berger. YearICSDICDDSMDevelopment1955ICD-7RDisturbance of sleep was seen as a symptom of other diseases1965ICD-8Recognized as both a disease and a symptom of other diseases1968DSM-IIDisorder of Sleep as an independent category1975ICD-9Organic sleep disorder, nonorganic sleep disorder and as symptom of other diseases1979NosologyClinical classification into four major groups: Disorder of initiating and maintaining sleep (DIMS) - Insomnias, Disorder of Excessive sleep (DOES) - Hypersomnias, Disorder of sleep-wake schedule (Circadian rhythm disorders) and Parasomnias1980ICD-CMDSM-IIIManifestation of other disorders with physical manifestation, as Sleep walking and Sleep terror1987DSM-III-RSleep Disorders were classified into dysomnias and parasomnias.1990ICSDExpanded previous system into Dysomnias, Parasomnias, Symptomatic and Proposed disorder of sleep1990ICD-10Organic sleep disorders included under nervous system disorder, nonorganic under psychiatric disorders and a third category as manifestation of other diseases1994DSM-IVDyssomnias, Parasomnias, Manifestation of mental disorders and Other1997ICSD-RFirst detailed classification of various sleep disorders Dyssomnias Intrinsic Sleep Disorders Extrinsic Sleep Disorders Circadian Rhythm Sleep Disorders Parasomnias Arousal Disorders Sleep-Wake Transition Disorders Parasomnias Usually Associated with REM Sleep Other Parasomnias Sleep Disorders Associated with Mental, Neurologic, or Other Medical Disorders Associated with Mental Disorders Associated with Neurologic Disorders Associated with Other Medical Disorders 4. Proposed Sleep Disorders2000DSM-IV-TR Primary sleep disorders Dyssomnias Insomnias Hypersomnias Recurrent Hypersomnias Narcolepsy Breathing related sleep disorder Circadian rhythm sleep disorders Movement disorder of sleep Parasomnias Secondary sleep disorders associated with other mental disorders and substance use.2005ICSD-2Most extensive classification of sleep disorders2010ICD-10-CMThree major categories, F51 as nonorganic sleep disorders, G47 organic sleep disorders and R- as symptoms of sleep disorders2013ICSD-3DSM-VLumping and splitting of sleep disorders and concordance of two systems2015ICD-11 BetaProposed beta version yet to be finalized in line with ICDS3 and DSM V

Validity and reliability

Diagnoses of sleep disorders are based on self-assessment questionnaires, clinical interview, physical examination and laboratory procedures. The validity and reliability of various sleep disorders are yet to be proved and need further research within the ever-changing field of sleep medicine. Admittedly, the development of sleep disorder classification remains as much an art as it is a science.

The International Classification of Sleep Disorders (ICSD)

The International Classification of Sleep Disorders (ICSD) was produced by the American Academy of Sleep Medicine (AASM) in association with the European Sleep Research Society, the Japanese Society of Sleep Research, and the Latin American Sleep Society. The classification was developed as a revision and update of the Diagnostic Classification of Sleep and Arousal Disorders (DCSAD) that was produced by both the Association of Sleep Disorders Centers (ASDC) and the Association for the Psychophysiological Study of Sleep and was published in the journal Sleep in 1979. Disorder of initiating and maintain sleep (DIMS) - Insomnias Disorder of Excessive sleep (DOES) - Hypersomnias Disorder of sleep wake schedule Parasomnias The International Classification of Sleep Disorders (ICSD) uses a multiaxial system for stating and coding diagnoses both in clinical reports or for data base purposes. The axial system uses International Classification of Diseases (ICD-9- CM) coding wherever possible. Additional codes are included for procedures and physical signs of particular interest to sleep disorders clinicians and researchers. Diagnoses and procedures are listed and coded on three main "axes." The axial system is arranged as follows: Axis A ICSD Classification of Sleep Disorders Axis B ICD-9-CM Classification of Procedures Axis C ICD-9-CM Classification of Diseases (nonsleep diagnoses).

ICSD - I Revised 1997

Dyssomnias Intrinsic Sleep Disorders Extrinsic Sleep Disorders Circadian Rhythm Sleep Disorders

Parasomnias Arousal Disorders Sleep-Wake Transition Disorders Parasomnias Usually Associated with REM Sleep Other Parasomnias

Sleep Disorders Associated with Mental, Neurologic, or Other Medical Disorders Associated with Mental Disorders Associated with Neurologic Disorders Associated with Other Medical Disorders

Proposed Sleep Disorders

ICSD 2 is tabulated in the main article International Classification of Sleep Disorders

ICSD - 3

The last edition of ICSD-3 is a unified classification of sleep disorders. It includes seven major categories: insomnia disorders, sleep-related breathing disorders, central disorders of hypersomnolence, circadian rhythm sleep-wake disorders, sleep-related movement disorders, parasomnias, and other sleep disorders. Each of these categories has several subgroups:

1. Insomnia Chronic insomnia disorder Short-term insomnia disorder Other insomnia disorder

2. Sleep-related breathing disorders Obstructive sleep apnea (OSA) disorders OSA, adult OSA, pediatric Central sleep apnea syndromes Central sleep apnea with Cheyne-Stokes breathing Central sleep apnea due to a medical disorder without Cheyne-Stokes breathing Central sleep apnea due to high altitude periodic breathing Central sleep apnea due to a medication or substance Primary central sleep apnea Primary central sleep apnea of infancy Primary central sleep apnea of prematurity Treatment-emergent central sleep apnea Sleep-related hypoventilation disorders Obesity hypoventilation syndrome Congenital central alveolar hypoventilation syndrome Late-onset central hypoventilation with hypothalamic dysfunction Idiopathic central alveolar hypoventilation Sleep-related hypoventilation due to a medication or substance Sleep-related hypoventilation due to a medical disorder Sleep-related hypoxemia disorder Isolated symptoms and normal variants

3. Central disorders of hypersomnolence Narcolepsy type 1 Narcolepsy type 2 Idiopathic hypersomnia Kleine-Levin syndrome Hypersomnia due to a medical disorder Hypersomnia due to a medication or substance Hypersomnia associated with a psychiatric disorder Insufficient sleep syndrome

4. Circadian rhythm sleep-wake disorders Delayed sleep-wake phase disorder Advanced sleep-wake phase disorder Irregular sleep-wake rhythm disorder Non-24-h sleep-wake rhythm disorder Shift work disorder Jet lag disorder Circadian sleep-wake disorder not otherwise specified

5. Sleep-related movement disorders Restless legs syndrome Periodic limb movement disorder Sleep-related leg cramps Sleep-related bruxism Sleep-related rhythmic movement disorder Benign sleep myoclonus of infancy Propriospinal myoclonus at sleep onset Sleep-related movement disorder due to a medical disorder Sleep-related movement disorder due to a medication or substance Sleep-related movement disorder, unspecified Isolated symptoms and normal variants Excessive fragmentary myoclonus Hypnagogic foot tremor and alternating leg muscle activation Sleep starts (hypnic jerks)

6. Parasomnias NREM-related parasomnias Confusional arousals Sleepwalking Sleep terrors Sleep-related eating disorder REM-related parasomnias REM sleep behavior disorder Recurrent isolated sleep paralysis Nightmare disorder Other parasomnias Exploding head syndrome Sleep-related hallucinations Sleep enuresis Parasomnia due to a medical disorder Parasomnia due to a medication or substance Parasomnia, unspecified Isolated symptoms and normal variants Sleep talking

7. Other sleep disorders

International Classification of Disease (ICD)

ICD-7R 1955 780.7 Disturbance of sleep

ICD-8 1965

306.4 Specific disorder of sleep 780.6 Disturbance of sleep

ICD-9 1975

327 Organic sleep disorders

327.0 Organic disorders of initiating and maintaining sleep [organic insomnia] 327.00 Organic insomnia, unspecified