Sample Size We aim to recruit 40 patients into each group (total n=120). The sample size calculation for the study was conducted based on the within group standard deviation of 7 (this was the upper limit of the standard deviation for the bipolar patients HAMD scores in the low frequency right sided rTMS trial data provided above) and between group difference of 5.0 points (change in 2 active groups of 12 (based on 4 week change data above) and change of 7 in the sham group allowing for a substantial placebo response). With an alpha of 0.05 the study will have a power of 0.91 to detect a difference in end scores between the 3 groups (calculation in PASS 8.0).