Final answer:
Stimulants are drugs that increase alertness, attention, and energy by stimulating the brain and increasing neural activity.
Step-by-step explanation:
The category of drugs known to increase alertness, attention, and energy is stimulants. Stimulants are a type of psychoactive drug that stimulates the brain, leading to increased levels of neural activity. Many stimulants act as agonists of the dopamine neurotransmitter system, which is often associated with reward and craving. Examples of stimulants include caffeine, nicotine, cocaine, and amphetamines such as Adderall. These compounds can block the reuptake of dopamine, thus heightening the stimulation of the central nervous system.