Passionflower appears to act on the gamma-aminobutyric acid (GABA) pathway system. By increasing levels of GABA, brain cell activity is decreased, leading to calming and sedating effects.[1]
Passionflower also contains flavonoids[2] that have anti-inflammatory and antioxidant properties, as well as indole alkaloids. The latter may be responsible for the antidepressant and anxiolytic effects of passionflower, although more research is needed to clarify their role.[3]