The International Classification of Sleep Disorders divides sleep disorders into four major categories: dyssomnias, parasomnias, sleep disorders associated with medical and psychiatric disorders, and proposed sleep disorders. 22


Dyssomnias are disturbances in the amount, timing, or quality of sleep. These disorders result in excessive daytime sleepiness or insomnia. The International Classification of Sleep Disorders22 lists three categories: intrinsic sleep disorders, extrinsic sleep disorders, and circadian rhythm sleep disorders:


  • Intrinsic sleep disorders:
    • Psychophysiologic insomnia
    • Sleep state misperception
    • Idiopathic insomnia
    • Narcolepsy
    • Recurrent hypersomnia
    • Idiopathic hypersomnia
    • Post-traumatic hypersomnia
    • Obstructive sleep apnea syndrome
    • Central sleep apnea syndrome
    • Central alveolar hypoventilation syndrome
    • Periodic limb movements in sleep disorder
    • Restless legs syndrome
    • Intrinsic sleep disorder not otherwise specified
  • Extrinsic sleep disorders:
    • Inadequate sleep hygiene
    • Environmental sleep disorder
    • Altitude insomnia
    • Adjustment sleep disorder
    • Insufficient sleep syndrome
    • Limit-setting sleep disorder
    • Sleep-onset association disorder
    • Food allergy insomnia
    • Nocturnal eating (drinking) syndrome
    • Hypnotic-dependent sleep disorder
    • Stimulant-dependent sleep disorder
    • Alcohol-dependent sleep disorder
    • Toxin-induced sleep disorder
    • Extrinsic sleep disorder not otherwise specified
  • Circadian rhythm sleep disorders:
    • Time zone change (jet lag) syndrome
    • Shift-work sleep disorder
    • Irregular sleep-wake pattern
    • Delayed sleep phase syndrome
    • Advanced sleep phase syndrome
    • Non–24-hour sleep-wake disorder
    • Circadian rhythm sleep disorder not otherwise specified


In parasomnias, abnormal events occur during sleep. Many mimic epileptic seizures. The International Classification of Sleep Disorders22 lists the following parasomnias:

  • Arousal disorders:
    • Confusional arousals
    • Sleepwalking
    • Sleep terrors
  • Sleep-wake transition disorders:
    • Rhythmic movement disorder
    • Sleep starts
    • Sleeptalking
    • Nocturnal leg cramps
  • Other parasomnias:
    • Sleep bruxism
    • Sleep enuresis
    • Sleep-related abnormal swallowing syndrome
    • Nocturnal paroxysmal dystonia
    • Sudden unexplained nocturnal death syndrome
    • Primary snoring
    • Infant sleep apnea
    • Congenital central hypoventilation syndrome
    • Sudden infant death syndrome
    • Benign neonatal sleep myoclonus
    • Other parasomnias not otherwise specified
  • Parasomnias usually associated with rapid eye movement (REM) sleep:
    • Nightmares
    • Sleep paralysis
    • Impaired sleep-related penile erections
    • Sleep-related painful erections
    • REM sleep–related sinus arrest
    • REM sleep behavior disorder

Lists adapted from The International Classification of Sleep Disorders Diagnostic and Coding Manual. Rochester, MN: American Sleep Disorders Association, 1990:15–17. 
Adapted from: Malow, BA, and Vaughn BV. Sleep disorders and epilepsy. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;258.
With permission from Elsevier ( 

Reviewed By: 
Steven C. Schachter, MD
Thursday, April 1, 2004