Passionflower (Passiflora incarnata) has a long history of use in traditional herbal medicine, particularly in Europe and North America, as a remedy for nervousness, anxiety, and sleep disturbances. Historically, it was used by Native American tribes and later adopted by European herbalists for its calming properties.

Modern scientific research has begun to investigate the efficacy of passionflower for nervousness and related conditions. Several small-scale clinical studies and randomized controlled trials have evaluated its anxiolytic (anxiety-reducing) effects. Some studies report that passionflower extracts may be as effective as certain conventional medications (such as oxazepam) for mild to moderate anxiety, with fewer side effects. The proposed mechanism involves modulation of gamma-aminobutyric acid (GABA) activity in the brain, leading to central nervous system relaxation.

However, the overall quality of the evidence is limited by small sample sizes, short duration, and variability in the preparations used. Systematic reviews and meta-analyses generally conclude that while passionflower shows promise as a mild anxiolytic, more high-quality research is needed to confirm its efficacy and safety. Thus, while there is some scientific support for its use in managing nervousness, the evidence is not robust enough to warrant a higher rating.