Classifying Sleep Disorders

The diagnosis of sleep disorders and disturbances is based on clinical questionnaires, interviews, physical examinations and laboratory sleep research. Many guides and manuals are available today, to be used by doctors as a helping hand with recognizing various symptoms and pinpointing them to a certain sleep disorder.

The diagnosis of sleep disorders and disturbances is based on clinical questionnaires, interviews, physical examinations and laboratory sleep research. Many guides and manuals are available today, to be used by doctors as a helping hand with recognizing various symptoms and pinpointing them to a certain sleep disorder.

Even so, diagnosing disorders can be tricky. Many of them have overlapping symptoms amongst one another, conditions for diagnosing are less than ideal, not to mention the tendency of general practitioners and experts in different fields to assume that certain sleep disorders are symptoms of other medical conditions, rather than disorders on their own. In fact, a survey done in 1991 involved 37 American medical schools stated that sleep and sleeping disorders were covered on average for one or two hours in total; the perfect picture of where we stand when it comes to sleeping science.

The first book on the subject was released in 1850, written by Robert MacNish. It mentioned sleepwalking, sleep-talking, nightmares and sleeplessness. Fast-forward to 1924, Electroencephalography (EEG) was discovered, shortly followed by many other landmark discoveries (REM sleep and sleep apnea amongst others), shaping sleep science as we know it today. It allowed for a better understanding of many sleep disorders already known and discovering of new, unexplored ones. A few attempts have been made at organizing and differentiating between this mess of new information.

At this point, three organizational systems are largely at use around the world:

–          the International Classification of Diseases (ICD), written by the World Health Organization (WHO)

A “standard diagnostic tool for epidemiology, health management, and clinical purposes,” the ICD classifies a wide array of diseases and pins them to corresponding generic categories (including some sleep disorders) while pointing out possible variations and common complaints with patients. This “general rule of thumb” of the classification manuals is a good reference point for purposes of general practitioners and specialists alike.

–          the Diagnostic and Statistical Manual (DSM), developed by the American Psychiatric Association (APA)

This manual is mainly made for use by mental health professionals and general practitioners. A common mental health disorder guide, it also covers general health, including sleep-related issues, although not in such detail as the ICSD.

–          the International Classification of Sleep Disorders (ICSD)-3, by the American Academy of Sleep Medicine (AASM), intended for sleep specialists.

Universally followed by sleep specialists and researchers, this manual finally provides the in-detail, distinctive approach to sleep medicine that previously lacked in the healthcare system. It is this system that we will break down in more detail below, from its first version in 1979 to the advanced last one that is used presently, along with some established diagnosis and treatment strategies used by doctors around the world.

Evolution of the currently used classification system

The first extensive classification of sleep disorders, intended for sleep specialists and general practitioners of medicine, called Diagnostic Classification of Sleep and Arousal Disorders (DCSAD), outed in 1979. It grouped disorders based on their symptoms and formed the basis of the classification system still used today. Although the manual helps to understand the basic approach to diagnosing sleeping disorders, back then, due to the limitations of research methods, the causes of many sleeping disorders were still largely unknown. Because of this problem, a new manual, called International Classification of Sleep Disorders (ICSD), was published in 1990 through the combined efforts of American Academy of Sleep Medicine (AASM), European Sleep Research Society, Latin American Sleep Society and the Japanese Society of Sleep Research. This edition updated and resolved many of the first edition’s misconceptions and was a huge success. The next edition, ICDS-2, only minorly edited and improved the ICDS from 1990, and was published in 2005. Finally, the latest revision, the ICDS-3, outed in 2014 and remains the most authoritative clinical manual for diagnostic of sleep disorders to date.

Diagnostic Classification of Sleep and Arousal Disorders (DCSAD)

The first diagnostic manual was written by the Association of Sleep Disorders Centers (ASDC), in collaboration with the Association for the Psychophysiological Study of Sleep. In this manual, sleeping disorders were placed into three symptom-based groups:

–          Disorder of initiating and maintaining sleep (DIMS)  – Insomnias

–          Disorder of Excessive sleep (DOES) – Hypersomnias

–          Parasomnias

Due to the sudden and significant growth in the field, sleep specialists were able to reevaluate and expand the previous grasp of sleeping disorders, so a revision of the first classification system was necessary.

International Classification of Sleep Disorders (ICSD)

This adjusted edition of the first manual was, at the time, very useful for differential diagnosis of the disorders, introducing the previously lacking pathophysiological aspect into the picture – it acknowledged the possibilities of association between sleep disorders and other conditions, like mental, neurological and other medical disorders.

International Classification of Sleep Disorders (ICDS)-2

In 2005 came out the minorly improved, redone edition of the ICDS. It listed eight categories consisting of a total of 81 sleep disorders, with their symptoms described in detail and including precise, distinctive diagnostic criteria. Additionally, it presented other notable issues like the diagnosis of sleep disorders connected to non-sleep disorders and stated some psychiatric disorders that frequently come hand in hand with certain sleep disorders.

The categories listed were as following:

1.The insomnias, including adjustment sleep disorder (acute insomnia), psychophysiological insomnia, paradoxical insomnia (formerly sleep state misperception) and seven others;

2.The sleep-related breathing disorders, with five subgroups and a total of fourteen disorders;

3.The hypersomnias of central origin, consisting of twelve disorders;

4.The circadian rhythm sleep disorders, nine disorders, including jet-lag type, advanced sleep phase type, delayed sleep phase type, etc;

5.The parasomnias, with three subgroups: Disorders of arousal (from non-REM sleep), Parasomnias usually associated with REM sleep and Other parasomnias;

6.The sleep-related movement disorders, covering eight disorders;

7.Isolated symptoms,unresolved issues, and apparently normal variants such as long sleep, short sleep, snoring, sleep-talking and five more;

8.Other sleep disorders, with three different disorders

International Classification of Sleep Disorders (ICSD)-3

Published in 2014, the latest revision of the dominant classification method cleared up some issues and disagreements that the international sleep specialist society brought up in the last decade. This version categorizes sleep disorders into six respective categories:

  • Insomnia
  • Sleep-Related Breathing Disorders
  • Central Disorders of Hypersomnolence
  • Circadian Rhythm Sleep-Wake Disorders
  • Parasomnias
  • Sleep-Related Movement Disorders

Some of the changes made comparing to the ICDS-2 include separating narcolepsy into two types and changing the criteria for grouping disorders from symptom-based to pathophysiology-based.

Methods commonly used for diagnosing sleep disorders

The first step to every diagnosis is carefully taking the patient’s medical history (noting all previously or currently used medication, possible past diagnosis, and attempts at treatment), considering patient’s age and current health state, and being open to the possibility of another condition – it is important to determine whether a sleep-related symptom or disorder is secondary to a psychiatric condition if there is one, and vice versa. These distinctions greatly influence any future treatment plans.

A sleep log maintained by the patient for a minimum of two consecutive weeks may help measure the type and level of disturbances in a normal environment, although with the obvious flaw of being subjective. A parallel diary by a partner might also be useful.

The Epworth Sleepiness Scale (ESS) is a tool used to determine daytime sleepiness levels, useful for keeping track of therapy progress.

An actigraph might be used for a few weeks. It’s a motion-sensing tool that helps with sleep-wake cycle evaluation and regularly complements sleep journals. It is also recommended in case a polysomnography test isn’t available or necessary for the diagnosis.

Polysomnography is a multi-parametric test used to confirm or rule out sleep apnea and some other disorders. It is performed in a laboratory at a time when the patient would usually sleep at home; it monitors sleep stages and respiration, showing EEG (electroencephalogram), EOG (electrooculogram), ECG (electrocardiogram), movements of patient’s chest, legs, airflow (nasal and oral) and blood oxygen levels in the body.

A Multiple Sleep Latency Test (MSLT) is a test usually following after a polysomnogram, with all its equipment still positioned as they were during the night. MSLT is used to measure daytime sleepiness; the patient is held during the whole day and offered to nap every other hour. When that happens, MSLT measures how quickly the patient falls asleep, and whether or not the REM stage was present during the nap, which would be a sign of narcolepsy.

Possible treatment plans for different conditions

It is imperative that a doctor determines whether the patient’s disordered sleep is primary or secondary to another medical condition. When it is secondary, diagnosis and treatment of the root problem is the first line of action; treatment of the sleep disorder at the same time as the primary condition might be required.

In situations where a diagnosis isn’t definitive, the first line of action is usually consisting of a good sleep hygiene plan and potentially implementing cognitive behavioral therapy (CBT). These methods are pill-free and can’t hurt. CBT consists of methods aiming to relax the patient, help them learn to associate the bed with sleep, limit their time in bed to nighttime and deal with any issues or questions they have about sleep.

For narcolepsy, idiopathic hypersomnia, acute insomnia, certain parasomnias, and some other conditions, pharmacotherapy is necessary and effective.

Various Continuous Positive Airway Pressure (CPAP) devices are indicated for nightly, at-home use for sleep apnea and other sleep-related breathing disorders, ensuring the airways remain open during sleep. In more severe cases, surgery might be required.

Carefully timed bright light and darkness therapy, accompanied by a supplement of melatonin, effectively treats chronic circadian rhythm disorders (delayed sleep onset being the most frequently faced). Two other universally suggested strategies for circadian rhythm disorders include stimulants, and Chronotherapy, which works by moving the patient’s time for sleep and waking up by a little bit every day until they reach a normal bedtime hour. In case the patient decides to accept and schedule their activities around the delayed sleep onset disorder, treatment isn’t needed. The proof of the diagnosis is enough to help the patient avoid having scheduled appointments and responsibilities in their specific bedtime.

But what about children?

Studies done on the subject reveal that from 25%, up to 50% of children experience sleep-related problems during their childhood. Disordered sleeping is linked to behavioral concerns, and more common in children and adolescents with other chronic issues like psychiatric, medical or neurodevelopmental conditions.

There is a number of sleep disorders known to be prevalent in children:

  • Obstructive sleep apnea
  • Sleepwalking
  • Confusional arousals
  • Nightmares
  • Behavioral insomnia of childhood
  • Restless leg syndrome
  • Delayed sleep phase disorder

When diagnosing children, doctors need to keep in mind that their normal sleeping patterns aren’t the same as those in adults, along with their expected physical and developmental stages through childhood. Pediatric obstructive sleep apnea is the most alarming disorder when it comes to children. Immediate treatment is required; other disordered sleep experiences, although maybe scary to the child, often resolve on their own, or with a little support of improved sleep hygiene.

The classification system of sleep disorders in children isn’t often encountered in the form of a separate manual; sleeping disorders are rather included in general practitioners’ and pediatricians’ guides, but many websites and articles offer a wide palette of information to help doctors recognize and treat any potential sleep issue in children.

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