What is Serotonin?
Serotonin (5-HT) is a neuromodulator that influences mood, impulse control, sleep, appetite, social behavior, and cognition. It is the target of the most widely prescribed class of antidepressants (SSRIs) and plays a complex role in behavioral regulation.
How it works
Serotonin is produced primarily in the raphe nuclei of the brainstem and projects throughout the brain. Its behavioral effects are complex and context-dependent: serotonin promotes patience (waiting for delayed rewards), inhibits impulsive aggression, and contributes to prosocial behavior. The serotonin system interacts extensively with the dopamine system: while dopamine signals reward and motivation, serotonin modulates the time horizon over which rewards are evaluated. Low serotonin is associated with impulsivity, aggression, and depression.
Applied example
SSRIs (selective serotonin reuptake inhibitors) increase serotonin availability in the synapse. Patients taking SSRIs often report not just improved mood but also reduced impulsivity, decreased irritability, and greater patience, reflecting serotonin’s broad role in behavioral regulation beyond just mood.
Why it matters
Serotonin is the brain’s behavioral regulator, modulating the speed, intensity, and time horizon of behavioral responses, explaining why its disruption produces such wide-ranging psychological effects.
