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Somnolence (or "drowsiness") is a state of near-sleep, a strong desire for sleep, or sleeping for unusually long periods (c.f. hypersomnia). 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 the use of prescription medications such as mirtazapine or zolpidem.

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

[edit] Hazards

Sleepiness 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.

[edit] Illness

The human body can become sleepy in response to infection.^[1] Such somnolence is one of several sickness behaviors or reactions to infection that some theorize evolved to promote recovery by conserving energy while the body fights the infection using fever and other means.^[2][3]

[edit] Associated conditions

This list is incomplete; you can help by expanding it.

• advanced sleep phase syndrome
• brain edema
• cerebral hypoxia
• clinical depression, especially seasonal affective disorder (SAD)
• delayed sleep phase syndrome
• diabetes - ketoacidos as example, but not balansed diabetes melliitus
• encephalitis - (viral, bacterial or other agents)
• hydrocephalus
• hypothermia
• hypothyroidism
• infectious mononucleosis (glandular fever)
• intracranial hemorrhage such as due to ruptured aneurysm
• increased intracranial pressure; for example, due to brain tumors
• Lyme disease (borreliosis)
• medications
  • analgesics - mostly prescribed or illicit opiates such as OxyContin or heroin
  • anticonvulsants / antiepileptics - such as phenytoin (Dilantin), carbamazepine (Tegretol), lamotrigine (Lamictal), Lyrica (pregbalin), Gabapentin
  • antidepressants - for instance, sertraline, venlafaxine and fluoxetine
  • antihistamines - for instance, diphenhydramine (Benadryl)
  • antipsychotics - for example, thioridazine, quetiapine, and olanzapine (Zyprexa), but not haloperidol
  • dopamine agonists used in the treatment of Parkinson's disease, e.g. pergolide and ropinirole and Mirapex, used to treat restless leg syndrome.
  • HIV medications - for example, Sustiva and medications containing efavirenz
  • hypertension medications - such as Norvasc
  • tranquilizers / hypnotics - especially benzodiazepines, such as temazepam (Restoril) or nitrazepam (Mogadon), and barbiturates, such as amobarbital (Amytal) or secobarbital (Seconal)
  • other agents impacting the central nervous system, in sufficient or toxic doses
• Narcolepsy
• Sickness behavior
• sleep apnea
• sleep deprivation / insomnia
• starvation
• stroke
• traumatic brain injury
• trypanosomiasis
• epilepsy - after seisure

[edit] See also

Look up somnolence or drowsiness in Wiktionary, the free dictionary.

• Insomnia
• Hypersomnia
• Dyssomnia
• Fatigue (physical)
• Postprandial somnolence
• Restless legs syndrome
• Periodic Limb Movement

[edit] References

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