A complete list of all the sleep disorders listed in the second edition of the official diagnostic manual, the International Classification of Sleep Disorders (ICSD)
Sleep medicine is a young and rapidly evolving science. It was only in 1953 that we started to understand sleep physiology with the discovery of REM (rapid eye movement) sleep.
So it’s not surprising that the task of categorizing sleep disorders was only undertaken a few decades ago. And it’s far from a finished project. The nosology (the way disorders are classified) of sleep medicine is far from fixed.
Conditions such as sleep apnea require a physiological approach to diagnosis and treatment, whilst other disorders may require the expertise of mental health professionals.
It’s unlikely we’ll arrive at a ‘unified theory’ of sleep medicine any time soon, but for now, the standard tool used by the majority of health professionals dealing with sleep disorders is the International Classification of Sleep Disorders (ICSD).
How do you define a sleep disorder?
The first attempt to classify sleep disorders came in 1979. The Diagnostic Classification of Sleep and Arousal Disorders, published in the newly formed journal, Sleep, was largely organized into symptomatic categories ie (insomnia, hypersomnia, and abnormal events occurring whilst sleep).
However, it was difficult to make a diagnosis based on pathophysiology (quantifiable measurement) because most of the causes of sleep disorders were unknown at the time.
By 1990, knowledge had progressed sufficiently to warrant a new classification. The International Classification of Sleep Disorders (ICSD) was published by the major international sleep societies at the time, a group comprising of the American Sleep Disorders Association (ASDA), European Sleep Research Society, the Japanese Society of Sleep Research, and the Latin American Sleep Society.
The ICSD comprised 84 separate disorders based on pathophysiological concepts. In 2002, the American Academy of Sleep Medicine set up a committee to further revise the classification resulting in the current classification, the ICSD-2.
ICSD – an international standard
The ICSD-2 was published with the goal of standardizing definitions of sleep disorders and creating a systematic approach to diagnosis. It is widely used by clinicians and researchers worldwide, improving research efforts throughout the international community by adhering to a recognised set standards.The ICSD-2 outlines the following goals:
To describe all currently recognised sleep and arousal disorders, and to base the description on scientific and clinical evidence.
To present the sleep and arousal disorders in an overall structure that is rational and scientifically valid
To render the sleep and arousal disorders as compatible with ICD-9 and ICD-10 as possible
ICSD-2 sleep disorder categories
As a result the ISCD-2 organises sleep disorders into the following eight categories.
Sleep Related Breathing Disorders
Hypersomnias of Central Origin Not Due to a Circadian Rhythm Sleep Disorder, Sleep Related Breathing Disorder or Other Cause of Disturbed Nocturnal Sleep