View source for Unconsciousness

{{See also|Unconscious mind}}
{{Short description|Loss of awareness of self and environment}}
{{More citations needed|date=June 2007}}{{Infobox medical condition (new)
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'''Unconsciousness''' is a state in which a living [[individual]] exhibits a complete, or near-complete, inability to maintain [[Spatial contextual awareness|an awareness of self and environment]] or to respond to any human or environmental [[Stimulus (physiology)|stimulus]].<ref>{{Cite web |title=MeSH Browser |url=https://meshb.nlm.nih.gov/#/record/ui?ui=D014474 |access-date=18 March 2018 |website=www.nlm.nih.gov}}</ref> Unconsciousness may occur as the result of [[traumatic brain injury]], [[Cerebral hypoxia|brain hypoxia]] (inadequate oxygen, possibly due to a brain [[infarction]] or [[cardiac arrest]]), severe intoxication with drugs that [[Depressant|depress the activity of the central nervous system]] (e.g., [[Alcohol (drug)|alcohol]] and other [[hypnotic]] or [[sedative]] drugs), severe [[fatigue]], [[pain]], [[Anesthesia|anaesthesia]], and other causes.

Loss of consciousness should not be confused with the notion of the [[Unconscious mind|psychoanalytic unconscious]], cognitive processes that take place outside awareness (e.g., [[implicit cognition]]), and with [[altered states of consciousness]] such as [[sleep]], [[delirium]], [[hypnosis]], and other altered states in which the person responds to stimuli, including [[trance]] and [[psychedelic experience]]s.

==Causes==
This is not a complete list.
===Cardiovascular system===
* [[Arrhythmia]] (irregular heart beat)
* [[Bleeding]]
* [[Cardiac arrest]]
* [[Cardiomegaly]]
* [[Heart failure]] (HF) (congestive heart failure (CHF))
* [[Myocardial infarction]] (MI) (heart attack)
* [[Myocarditis]]
* [[Pericarditis]]
* [[Shock (circulatory)|Shock]]
===Nervous system===
* [[Brain abscess]]
* [[Brain tumor]]
* [[Encephalitis]]
* [[Intracranial pressure|Increased intracranial pressure]]
* [[Intracerebral hemorrhage]] (hemorrhagic stroke)
* [[Stroke#Ischemic stroke|Ischemic stroke]]
* [[Meningitis]]
* [[Seizure]]
* [[Subarachnoid hemorrhage]]
* [[Traumatic brain injury]] (TBI) (intracranial injury)
===Respiratory system===
* [[Acute respiratory distress syndrome]] (ARDS)
* [[Choking]]
* [[Drowning]]
* [[Lung cancer]] (lung carcinoma)
* [[Pneumonia]]
* [[Pulmonary embolism]] (PE)
* [[Respiratory arrest]]
* [[Respiratory failure]]
===Other===
* [[Drugs]]
* [[Electrocution]]
* [[Kidney failure]]
* [[Liver failure]]
* [[Poison]] or [[venom]]
* [[Sepsis]]

==Law and medicine==
[[File:Person passed out on sidewalk photographed with a dutch angle NYC.tif|thumb|Person passed out on a sidewalk in New York City, 2008]]In [[jurisprudence]], unconsciousness may entitle the [[criminal defendant]] to the [[defense (legal)|defense]] of [[automatism (law)|automatism]], i.e. a state without control of one's own actions, an [[excuse|excusing condition]] that allows a defendant to argue that they should not be held criminally [[Legal liability|liable]] for their actions or [[omission (criminal law)|omissions]]. In most countries, courts must consider whether unconsciousness in a situation can be accepted as a defense; it can vary from case to case. Hence [[epileptic seizure]]s, [[neurology|neurological]] dysfunctions, and [[sleepwalking]] may be considered acceptable excusing conditions because the loss of control is not foreseeable, but falling asleep (especially while driving or during any other safety-critical activity) may not, because natural sleep rarely overcomes an ordinary person without warning.

In many countries, it is presumed that someone who is less than fully conscious cannot give [[consent]] to anything. This can be relevant in cases of [[sexual assault]], [[euthanasia]], or patients giving [[informed consent]] with regard to starting or stopping a medical treatment.

==See also==
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* [[Coma]]
* [[Do not resuscitate]]
* [[Greyout]]
* [[Hypnosis]]
* [[Living will]]
* [[Shallow water blackout]]
* [[Sleep]]
* [[Somnophilia]]
* [[Syncope (medicine)|Syncope]] (fainting)
* [[Trance]]
* [[Traumatic brain injury]]
* [[Twilight sleep]]
{{colend}}

== References ==
<references />{{Wikitionary|Unconsciousness}}{{Medical resources
| ICD11           = {{ICD11|MB20.1}}
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{{Disorders of consciousness}}
{{Consciousness}}

[[Category:Consciousness]]
[[Category:Symptoms and signs of mental disorders]]