Unconsciousness

See also:Unconscious mind

Unconsciousnessis a state in which a livingindividualexhibits a complete, or near-complete, inability to maintain anawareness of self and environmentor to respond to any human or environmentalstimulus.Unconsciousness may occur as the result oftraumatic brain injury,brain hypoxia(inadequate oxygen, possibly due to a braininfarctionorcardiac arrest), severe intoxication with drugs thatdepress the activity of the central nervous system(e.g.,alcoholand otherhypnoticorsedativedrugs), severefatigue,pain,anaesthesia,and other causes.

Unconsciousness
An unconscious male human lying in arecovery position
Specialty	Psychiatry Neurology Cardiology Pulmonology

Loss of consciousness should not be confused with the notion of thepsychoanalytic unconscious,cognitive processes that take place outside awareness (e.g.,implicit cognition), and withaltered states of consciousnesssuch assleep,delirium,hypnosis,and other altered states in which the person responds to stimuli, includingtranceandpsychedelic experiences.

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

Nervous system

• Brain abscess
• Brain tumor
• Encephalitis
• Increased intracranial pressure
• Intracerebral hemorrhage(hemorrhagic 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
• Poisonorvenom
• Sepsis

Law and medicine

Person passed out on a sidewalk in New York City, 2008

Injurisprudence,unconsciousness may entitle thecriminal defendantto thedefenseofautomatism,i.e. a state without control of one's own actions, anexcusing conditionthat allows a defendant to argue that they should not be held criminallyliablefor their actions oromissions.In most countries, courts must consider whether unconsciousness in a situation can be accepted as a defense; it can vary from case to case. Henceepileptic seizures,neurologicaldysfunctions andsleepwalkingmay 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 giveconsentto anything. This can be relevant in cases ofsexual assault,euthanasia,or patients givinginformed consentwith regard to starting or stopping a medical treatment.

See also

• Coma
• Do not resuscitate
• Greyout
• Hypnosis
• Living will
• Shallow water blackout
• Sleep
• Somnophilia
• Syncope(fainting)
• Trance
• Traumatic brain injury
• Twilight sleep