Somnolence

Somnolence
Classification and external resources
ICD-10	R40.0
ICD-9	780.09

Somnolence (or "drowsiness") is a state of near-sleep, a strong desire for sleep, or sleeping for unusually long periods (cf. 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. Somnolence goes back to the Latin "somnus" meaning "sleep."

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.

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]

Associated conditions

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

• advanced sleep phase syndrome

• Alice in Wonderland syndrome
• brain edema
• cerebral hypoxia
• Chronic Mental Fatigue Syndrome
• clinical depression, especially seasonal affective disorder (SAD)
• delayed sleep phase syndrome
• diabetes – ketoacidosis as example, but not balanced diabetes mellitus
• encephalitis – (viral, bacterial or other agents)
• epilepsy – after seizure
• hydrocephalus
• hyperparathyroidism
• 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) and doxylamine(Unisom-2)
  • antipsychotics – for example, thioridazine, quetiapine, and olanzapine (Zyprexa) and haloperidol and Geodon.
  • 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
  • Hormone replacement therapy (male-to-female)^[4]
  • 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

See also

• Chronic Fatigue Syndrome
• Decision fatigue
• Insomnia
• Hypersomnia
• Dyssomnia
• Fatigue (physical)
• Postprandial somnolence
• Restless legs syndrome
• Periodic limb movement
• Later stages of Hepatic Encephalopathy
• The Drowsy Chaperone

References

1. ^ Mullington, J.; Korth, C.; Hermann, D.M.; Orth, A.; Galanos, C.; Holsboer, F.; Pollmacher, T. (2000) "Dose-dependent effects of endotoxin on human sleep". Am J Physiol Regul Integr Comp Physiol. 278: R947–955 PubMed
2. ^ Hart, B.L. (1988) "Biological basis of the behavior of sick animals". Neurosci Biobehav Rev. 12: 123–137. PubMed
3. ^ Kelley, K.W.; Bluthe, R.M.; Dantzer, R.; Zhou, J.H.; Shen, W.H.; Johnson, R.W.; Broussard, S.R. (2003) "Cytokine-induced sickness behavior". Brain Behav Immun. 17 Suppl 1: S112–118 PubMed
4. ^ The World Professional Association for Transgender Health's Standards of Care, 6th version