Levels of Consciousness preconscious- ideas are not in your awareness right now, but you could recall them if you had to unconscious (aka subconscious)- unavailable to awareness under most circumstances; info is hidden nonconscious- basic biological functions Altered States of Consciousness- in which a person?s sense of self or sense of the world changes. An example would be sleep. Circadian Rhythms- biological clocks Functions of Sleep- revive body, resist infection, recover from stress Biofeedback- a system that provides information about something happening in the body Classes of Drugs Depressants- drugs that slow the activity of the nervous system Alcohol Narcotics- relieve pain and induce sleep. Includes morphine, heroin, and codeine.