Altered States

States of consciousness can be altered by the use of drugs. Antidepressants affect the midbrain, the area involved with the formation of mood. Thus they can prevent and help to cure depression. Stimulants, such as amphetamines, act on the reticular-activating system, or RAS, and the hypothalamus. Their effect is to decrease fatigue, increase alertness and elevate mood. If the mind is overactive and, therefore, anxious, tranquilizers may be used to reduce the level of anxiety. They act principally on the limbic system and the RAS. Sedatives, for example barbiturates, are a group of drugs often administered as sleeping pills. They act on the RAS and on the cortex to reduce the conscious experiences that would normally induce wakefulness.