St. John's Wort is reputed to have an effect on depression, anxiety, sleep disorders.
St. John's Wort works like mono amine oxidase inhibitors - inhibiting the enzyme that breaks down neuro chemicals.
St. John's Wort contains a pigment that can cause phototoxicity in high doses.
BMJ 1996;313:241,253
The relevant product monographs must be regarded as the appropriate sources of prescribing information.