St John's Wort
is a herbal remedy that has been used for hundreds of years to treat mental health problems. Today it is mainly used as an over-the-counter remedy to treat mild and moderate depression, and sometimes seasonal affective disorder (SAD), mild anxiety and sleep problems.
The botanical name for St John's wort is Hypericum perforatum, and it is sometimes marketed and sold as 'Hypericum'. It contains many active substances, including hypericin and hyperforin, which are thought to affect mood.