Levels and quality of consciousness
Levels of consciousness can vary between alertness and coma (e.g., awake attention vs. sleep) It is correlated with patterns of electrical activity in the brain (brain waves). Quality of consciousness can vary (e.g., stupor, unconsciousness, sleep).
The complete awareness is an ability to be conscious of, feel or perceive; a condition of having knowledge or perception of a situation or fact.
Alertness is a state of being intellectually active. Alpha waves are common to people who are awake and having a frequency of 8 to 13 Hz.
Arousal/psychological arousal is a state of behavioural or physiologic activation; a state of excitation of the ascending reticular activating system, leading to the condition of alertness and readiness to respond, with the evidences of increased heart rate and blood pressure, GSR (galvanic skin response), desynchronized EEG (electroencephalography) activity.
Examples are Sexual arousal, Sleep disorders/Sleep apnoea.
An abrupt change from a deep stage of NREM (non-rapid eye movement) sleep to a lighter stage, or from REMS (Rapid Eye Movement sleep) to awake, with the possibility of awakening as the final outcome; arousal may be accompanied by higher tonic EMG (electromyography) activity and heart rate, as well as body movements; the interruption of sleep by continuous alpha activity and higher EMG activity of more than 3 sec.
Altered state of consciousness is an abnormal form of consciousness, when the mind can be aware but is not in its usual wakeful condition, including derealisation, depersonalization, a state of hypnosis, oceanic feeling, peak experience, a state of intoxication with a hallucinogen or euphoriant drug. A synonymous phrase is altered state of awareness (12).
Marginal consciousness is the portion of consciousness that is not in focus of attention and of which one is only dimly aware.
Sleep paralysis: Transition state from wakefulness to sleep, may be accompanied by Sleep paralysis, a condition of wake state with experience of REM atonia, often out-of-body experience, hypnagogic and hypnopompic images.
Hypnagogic images are dreamlike images accompanied by sleep paralysis, experienced by a person in the transition state from wakefulness to sleep.
Hypnopompic images are dreamlike images accompanied by sleep paralysis, experienced by a person in the transition state from sleep to wakefulness.
Stupor is a condition in which a person is immobile, mute, and unresponsive. In neurology it is a condition of impairment of consciousness.
Coma is the most extreme form of impaired consciousness, can be graded by the type of EEG (electroencephalography) activity.
Oneiroid is the state of impaired consciousness, a dream-like condition.
Twilight state is the state of impaired consciousness, a prolonged oneiroid state.