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), 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.
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
327.01 Insomnia due to medical condition classified elsewhere
327.02 Insomnia due to mental disorder
327.09 Other organic insomnia
327.1 Organic disorder of excessive somnolence [organic hypersomnia]
327.10 Organic hypersomnia, unspecified
327.11 Idiopathic hypersomnia with long sleep time
327.12 Idiopathic hypersomnia without long sleep time
327.13 Recurrent hypersomnia
327.14 Hypersomnia due to medical condition classified elsewhere
327.15 Hypersomnia due to mental disorder
327.19 Other organic hypersomnia
327.2 Organic sleep apnea
327.20 Organic sleep apnea, unspecified
327.21 Primary central sleep apnea
327.22 High altitude periodic breathing
327.23 Obstructive sleep apnea (adult)(pediatric)
327.24 Idiopathic sleep related non-obstructive alveolar hypoventilation
327.25 Congenital central alveolar hypoventilation syndrome
327.26 Sleep related hypoventilation/hypoxemia in conditions classifiable elsewhere
327.27 Central sleep apnea in conditions classified elsewhere
Major Somnolence Disorder (Hypersomnia Not Elsewhere Classified) The following specifiers apply to Sleep-Wake Disorders where indicated: Specify if: Episodic, Persistent, Recurrent Specify if: Acute, Subacute, Persistent Specify current severity: Mild, Moderate, Severe