The International Classification of Sleep Disorders (ICSD) is written by and copyrighted by the American Academy of Sleep Medicine (AASM), a professional society of doctors. To get the "international: credibility, the AASM says other sleep societies: the European Sleep Research Society, the Japanese Society of Sleep Research, and the Latin American Sleep Society - although how much input these organizations have into the classification is not clear. The most recent ICSD is ICSD-2, released in 2005.
How valid is the ICSD? It's reasonably well received and used by the medical community (doctors, clinics, insurance companies, diagnostic clinics), although in medical coding the ICD system is used.
In the field of psychiatry the professional organization the American Psychiatric Association developed the DSM - Diagnostic and Statistical Manual of Mental Disorders. The latest edition, DSM-5, was released in 2013 and explicitly not embraced by the federal government's National Institutes of Health.
So there is no one authority in medicine, but the ICSD is functional enough that it is useful.
The ICSD divides sleep disorders into 8 categories:
Here is a list of the sleep disorders in ICSD-2.
The defintion and classification of diseases is contentious, caught up with emotion and money.
The World Health Organization produces the widely accepted International Classification of Diseases, which also covers sleep disorders as well as other somatic and psychiatric diseases.
This is the big rival to ICSD for classification of sleep problems. The most current ICD is ICD-10, released in 1992. ICD-11 is due for release in 2017.
Restless legs syndrome is classified under ICD-10 as G25.8
Apnea is G47.3 Pickwickian syndrome is classified in ICD-10 in a separate cateogy from apnea.
Narcolepsy is G47.4
Circadian rythym disorders are G47.2
Hypersomnia (organic) is G47.1
Insomnia is G47.0
Insomnia (nonorganic) is F51.0
Hypersomnia (nonorganic) is F51.1
Circadian rythym disorders (nonorganic) are F51.2
Sleepwaling is F51.3
Night terrors is F51.4
Definition of sleep.