Effects of Kampo herbal medicine on plasma melatonin concentration in patients

There are studies reporting that some natural products containing melatonin. Sleep disturbance and nocturnal polyuria are related to abnormal biorhythm. It is possible that Kampo medicine may influence biorhythm. We therefore examined the symptoms and plasma melatonin of patients treated with Rokumi-gan, Hachimi-jio-gan, Gosha-jinki-gan and Seishinrenshi-in. Furthermore, the concentration of four kampo medicines and crude drugs making up these formulations were investigated. Diurnal plasma melatonin was not affected by Rokumi-gan, but tended to be lowered by treatment with Hachimi-jio-gan, Gosha-jinkigan and Seishinrenshi-in. Melatonin was present in several extracts from crude drugs, namely Rehmanniae radix, Moutan cortex, Cinnamomi cortex, Aconiti tuber, Plantaginis semen, Scutellariae radix and Lycii radicis cortex.