Tolerance occurs when a reduced effectiveness is seen with repeated use of the drug. Physiological dependence occurs when the body becomes adjusted to and dependent on the substance, in part because neurotransmitters are depleted by frequent presence of the drug. A person with an addiction requires the drug in his or her body and suffers painful withdrawal symptoms if the drug is not present. Withdrawal symptoms such as shakes, sweats, nausea, and sometimes death may occur if the drug is not present in one s body. Varieties of Psychoactive Drugs a. Hallucinogens or psychedelics produce the most dramatic changes in consciousness by altering perception of the environment and one's inner awareness.
Opiates suppress physical sensation and response to stimulation.
Depressants slow down the mental and physical activity of the body by inhibiting central nervous system activity. Alcohol is a depressant. Stimulants are drugs that increase central nervous system activity, speeding up both mental and physical rates of activity. E. Adaptability of Consciousness. Consciousness is the active mental construction of incoming information into a meaningful, organized pattern of symbols.