Which of the following are classified as stimulants?

Amphetamines are classified as stimulants because they increase the levels of certain neurotransmitters in the brain, particularly dopamine and norepinephrine. This leads to heightened alertness, increased energy, and improved concentration. Stimulants like amphetamines are commonly used to treat attention deficit hyperactivity disorder (ADHD) and certain sleep disorders, as they effectively enhance focus and reduce fatigue. The stimulating effects are a hallmark of this class of drugs, differentiating them from other substances that may have sedative, hallucinogenic, or depressant effects.