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Unconsciousness may occur as the result of traumatic brain injury, brain hypoxia (inadequate oxygen, possibly due to a brain infarction or cardiac arrest), severe intoxication with drugs that depress the activity of the central nervous system (e.g., alcohol and other hypnotic or sedative drugs), severe fatigue, pain, anaesthesia, and other causes.
During a stroke, blood flow to part of the brain is restricted or blocked. An ischemic stroke, brain hemorrhage, or brain tumor may cause restriction of blood flow. Lack of blood to cells in the brain prevents oxygen from getting to the neurons, and consequently causes cells to become disrupted and die.
In psychoanalysis and other psychological theories, the unconscious mind (or the unconscious) is the part of the psyche that is not available to introspection. [1] Although these processes exist beneath the surface of conscious awareness, they are thought to exert an effect on conscious thought processes and behavior. [ 2 ]
Drug-induced comas are used to protect the brain during major neurosurgery, as a last line of treatment in certain cases of status epilepticus that have not responded to other treatments, [2] and in refractory intracranial hypertension following traumatic brain injury. [1] Induced coma usually results in significant systemic adverse effects.
An altered level of consciousness can result from a variety of factors, including alterations in the chemical environment of the brain (e.g. exposure to poisons or intoxicants), insufficient oxygen or blood flow in the brain, and excessive pressure within the skull. Prolonged unconsciousness is understood to be a sign of a medical emergency. [3]
In animals, including humans, the startle response is a largely unconscious defensive response to sudden or threatening stimuli, such as sudden noise or sharp movement, and is associated with negative affect. [1] Usually the onset of the startle response is a startle reflex reaction.
Neuropsychologist Dr. Sanam Hafeez, Psy.D, tells me, “Living in a constant stream of negative news can affect brain function as well as mental health.” I asked Hafeez about what’s going on ...
The underlying mechanism involves the nervous system slowing the heart rate and dilating blood vessels, resulting in low blood pressure and thus not enough blood flow to the brain. [2] Diagnosis is based on the symptoms after ruling out other possible causes. [3] Recovery from a reflex syncope episode happens without specific treatment. [2]