Passion Flower is a relaxing herb used for insomnia, anxiety and nervousness. It can help soothe nervous excitability and over-active brain. It is a sedative and anti-spasmodic, thus Passion Flower is useful for gastrointestinal complaints which may have a nervous origin such as IBS. Scientists believe Passion Flower works by increasing levels of a chemical called gamma aminobutyric acid (GABA) in the brain. GABA lowers the activity of some brain cells, making you feel more relaxed.