Somnolence

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Somnolence
ICD-10	R40.0
ICD-9	780.09

Template:Search infobox Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Pratik Bahekar, MBBS [2]

Overview

Somnolence (or "drowsiness") is a state of near-sleep, a strong desire for sleep, or sleeping for unusually long periods. It has two distinct meanings, referring both to the usual state preceding falling asleep, and the chronic condition referring to being in that state independent of a circadian rhythm. The disorder characterized by the latter condition is most commonly associated with users of prescription hypnotics, such as mirtazapine or zolpidem.

It is considered a lesser impairment of consciousness than stupor or coma.

Hypersomnia of Central Origin

Hypersomnia of central origin is a disorder of severe sleepiness arising from CNS dysfunction of sleep–wake states. It does not include OSA, circadian rhythm disorders.

• Narcolepsy
• Idiopathic hypersomnia: If excessive daytime sleepiness exists without narcolepsy or other sleep disorders.
• Recurrent hypersomnia: consists of menstrual-related hypersomnia and Kleine-Levin syndrome
• Behaviorally induced insufficient sleep syndrome (Sleep Deprivation)
• Hypersomnia due to other conditions:
  • Neurological disorders, including structural, vascular, traumatic, toxic, infectious, and metabolic encephalopathy. Especially when the brain-stem reticular formation or midline diencephalic structures are effected.
  • [Neuromuscular disorders], [peripheral neuropathies], [myotonic dystrophy] lead to central or obstructive [sleep apnea], pain, or PLMD which in turn can cause somnolence
  • Sleepiness may occur with acute infectious illness, mediated by cytokines, including interferon, interleukins, and tumor necrosis factor
  • Psychiatric disorders, like depression, can cause tiredness, fatigue, and lack of energy and somnolence.

Sleep Disorders

• Circadian Rhythm Sleep Disorder
  • Delayed Sleep-Phase Type
  • Jet Lag Type
  • Shift Work Type
• Parasomnias
  • Nightmare Disorder
• Dyssomnias
  • Primary Insomnia
  • Breathing related sleep disorder
  • Restless legs syndrome
  • Periodic Limb Movement Disorder

Other Causes

• Advanced sleep phase disorder
• African trypanosomiasis ("sleeping sickness")
• Alice in Wonderland syndrome
• brain edema
• Cerebral hypoxia
• Chronic fatigue syndrome
• Clinical depression, especially seasonal affective disorder (SAD)
• Dehydration
• Delayed sleep phase syndrome
• Diabetic ketoacidosis as example, but not balanced diabetes mellitus
• Encephalitis – (viral, bacterial or other agents)
• Epilepsy – after seizure
• Fibromyalgia
• Hydrocephalus
• Hyperparathyroidism
• Hypothermia
• Hypothyroidism
• Increased intracranial pressure; for example, brain tumors
• Infectious mononucleosis (glandular fever)
• Insomnia
• Intracranial hemorrhage such as due to ruptured aneurysm
• Lyme disease (borreliosis)
• Medications
  • Analgesics: mostly prescribed or illicit opiates such as oxycontin or heroin
  • Antiepileptics such as phenytoin, carbamazepine, gabapentin
  • Antidepressants: for instance sedating tricyclic antidepressants and mirtazapine. Somnolence is less common with SSRI and SNRI as well as MAOI.
  • Antihistamines: diphenhydramine and doxylamine
  • Antipsychotics: thioridazine, quetiapine, olanzapine, risperidone, and ziprasidone but not haloperidol
  • Dopamine agonists used in the treatment of parkinson's disease e.g. pergolide, ropinirole and pramipexole.
  • HIV medications for example, efavirenz
  • Antihypertensive medications like amlodipine
  • Hypnotics like zopiclone, or the benzodiazepine such as diazepam or nitrazepam and the barbiturate, such as amobarbital or secobarbital
  • Other agents impacting the central nervous system in sufficient or toxic doses
• Starvation
• Sleep apnea
• Stroke
• Traumatic brain injury
• Treatment of primary insomina may cause somnolence:
  • Flurazepam
  • Benzodiazepine
  • Quazepam
  • Estazolam
  • Temazepam
  • Triazolam
  • Benzodiazepine receptor agonists: Eszopiclone, Zolpidem, Zaleplon
  • Melatonin receptor agonists: Ramelteon

Hazards

Somnolence can be dangerous when performing tasks that require constant concentration, such as driving a vehicle. When a person is sufficiently fatigued, he or she may experience microsleeps (loss of concentration).

See also

• Chronic fatigue syndrome
• Fibromyalgia
• Insomnia
• Hypersomnia
• Dyssomnia
• Fatigue (physical)
• Restless legs syndrome