How are sleep disorders classified?

 

The International Classification of sleep disorders (ICSD) was put together for the purpose to "discriminate between disorders and to facilitate an understanding of symptoms, etiology, and pathophysiology that allows for appropriate treatment". Since the release of the first edition in 1990, the ICSD published a 2nd edition in 2005, and is now on its 3rd edition, published in 2014. Some of the biggest differences between the 2nd and 3rd editions are how the various sleep disorders were divided into categories. The 2005 edition used 3 broad categories to organize all of the sleep disorders under either dysommnias (disorders making getting to sleep or staying asleep difficult), parasomnias (disorders that intrude into the sleep process), and sleep disorders associated with a mental, neurologic, or other medical disorders (disorders whose symptoms are not primary unto themselves but caused by other conditions).

 

The updated 3rd edition now classifies sleep disorders under 6 major categories: insomnia, sleep related breathing disorders, central disorders of hypersomnolence, circadian rhythm sleep-wake disorders, parasomnias, and sleep related movement disorders.

 

The ICSD-3 Sleep Disorder Categories

 

1. Insomnia

The ICSD-3 defines insomnia as "a repeated difficulty with sleep initiation, duration, consolidation, or quality that occurs despite adequate opportunity and circumstances for sleep, and results in some form of daytime impairment."

 

 

The ICSD-3 groups insomnia into 4 major categories listed below.

 

a. Chronic insomnia disorder

b. Short-term insomnia disorder

c. Other insomnia disorder

d. Isolated symptoms and normal variant

 

2. Sleep-related breathing disorders

These disorders are divided into those of central origin (characterized by a lack of breathing effort) and those caused by an obstruction of the airways.

 

a. Obstructive sleep apnea disorders

1. Obstructive sleep apnea, adult

2. Obstructive sleep apnea, pediatric

 

b. Central sleep apnea syndrome

1. Central sleep apnea with Cheyne-Stokes breathing

2. Central sleep apnea due to a medical disorder w/o Cheyne-Stokes breathing

3. Central sleep apnea due to high altitude periodic breathing

4. Central sleep apnea due to medication or substance

5. Primary central sleep apnea

6. Primary central sleep apnea of infancy

7.  Primary central sleep apnea of prematurity

8. Treatment-emergent central sleep apnea

 

c. Sleep-related hypoventilation disorders

1. Obesity hypoventilation syndrome

2. Congenital central alveolar hypoventilation syndrome

3. Late-onset central hypoventilation with hypothalamic dysfunction

4. Idiopathic central alveolar hypoventilation

5. Sleep-related hypoventilation due to medication or substance

6. Sleep-related hypoventilation due to medical disorder

 

d. Sleep-related hypoxemia disorder

 

e. Isolated symptoms and normal variants

1. Snoring

2. Catathrenia

 

3. Central disorders of hypersomnolence

The ICSD-3 categorizes this class of sleep disorders as those in which "the primary complaint is daytime sleepiness not caused by disturbed nocturnal sleep or misaligned circadian rhythms."

 

a. Narcolepsy type I

b. Narcolepsy type II

c. Idiopathic hypersomnia

d. Kleine-Levin syndrome

e. Hypersomnia due to a medical disorder

f. Hypersomnia due to a medication or substance

g. Hypersomnia associated with a psychiatric disorder

h. Insufficient sleep syndrome

 

4. Circadian rhythm sleep-wake disorders

These disorders are characterized by a disturbance or disruption to the normal circadian rhythm, which causes patients to experience excessive daytime sleepiness, insomnia, or both.

 

a. Delayed sleep-wake phase disorder

b. Advanced sleep-wake phase disorder

c. Irregular sleep-wake rhythm

d. Non-24-hour sleep-wake rhythm disorder

e. Shift work disorder

f. Jet lag disorder

g. Circadian rhythm sleep-wake disorder not otherwise specified (NOS)

 

5. Parasomnias

A parasomnia is an unwanted physical movement or action during sleep. This group of disorders is classified by disorders or arousal from NREM sleep, those associated with REM sleep, and other parasomnias.

 

a. NREM-related parasomnias

1. Disorders of arousal from NREM sleep

2. Confusional arousals

3. Sleepwalking

4. Sleep terrors

5. Sleep-related eating disorders

 

b. REM-related parasomnias

1. REM sleep behavior disorder

2. Recurrent isolated sleep paralysis

3. Nightmare disorder

 

c. Other parasomnias

1. Exploding head syndrome

2. Sleep-related hallucinations

3. Sleep enuresis

4. Parasomnia due to medical disorder

5. Parasomnia due to medication or substance

6.  Parasomnia, unspecified

 

d. Isolated symptoms and normal variants

1. Sleep talking

 

6. Sleep-related movement disorders

This class of disorders is characterized by simple, often repetitive movements during sleep or wake that can disrupt the sleep of the patient, the patient's bed partner, or both.

 

a. Restless leg syndrome

b. Periodic limb movement disorder

c .Sleep related leg cramps

d. Sleep-related bruxism

e. Sleep-related rhythmic movement disorder

f. Benign sleep myoclonus of infancy

g. Propriospinal myoclonus at sleep onset

h. Sleep-related movement disorder due to medical disorder

i. Sleep-related movement disorder due to medication or substance

j. Sleep-related movement disorder, unspecified