Stimulants are pharmacological compounds which induce temporary changes to mental and physical conditions, usually relating to energy levels. Stimulants produce these effects by chemically boosting or inhibiting various activities of the central and peripheral nervous systems. These effects can be achieved via the production of neurohormones like norepinephrine and dopamine, as well as interaction/agonism/antagonism of specific receptor cells.
Stimulant benefits can include mental focus and alertness, greater motivation, sexual arousal, higher athletic endurance, and reduced appetite. Stimulants can also be powerful mood lifters. They can be used to treat a variety of cognitive disorders, such as OCD, ADHD, and depression. Under the technical definition for nootropics, stimulants are specifically precluded due to the prevalence of associated side effects. However, many users will stack stimulants with nootropics for improved benefits.