Final answer:
Amphetamines are examples of CNS Stimulants, which increase alertness and wakefulness by stimulating brain activity and affecting dopamine neurotransmission.
Step-by-step explanation:
Amphetamines are examples of CNS Stimulants. These drugs are known to stimulate the brain, resulting in increased alertness and wakefulness. Substances like caffeine, nicotine, cocaine, and specifically amphetamines such as Adderall are part of this group. In contrast, CNS depressants tend to calm the brain and reduce arousal, which is the opposite effect of stimulants. Amphetamines, including those like methamphetamine, have been noted to block the reuptake of dopamine and increase levels of neural activity, hence their categorization as stimulants rather than depressants, narcotic analgesics, or hallucinogens.