Final answer:
Stimulants are drugs that increase consciousness and alertness, commonly including caffeine, nicotine, cocaine, and amphetamines. While they can enhance mood and attention, excessive use can lead to serious side effects like anxiety and addiction.
Step-by-step explanation:
Stimulants are psychoactive drugs that increase consciousness, alertness, and wakefulness. Their effects on the brain often include increased levels of dopamine, which is associated with reward and motivation. As a result, these substances can also have a high potential for abuse.
The effects of stimulants on consciousness can manifest as increased attention, elevated mood, reduced appetite, and in some cases, feelings of euphoria. However, prolonged or excessive use of stimulants can result in negative side effects such as anxiety, paranoia, high blood pressure, and in severe cases, addiction and cardiovascular problems.