A fluorescent discharge lamp 1 has two glow mode electrodes 15 and 16 wound around it in a helical fashion. One circuit 21 drives the main electrodes 10 and 11 at opposite ends of the lamp at high levels of brightness. Another circuit 22 drives the glow mode electrodes 15 and 16 at low levels of brightness, at about 10MHz. At intermediate levels of brightness, both the main electrodes 10 and 11 and the glow mode electrodes 15 and 16 are driven, the two sets of electrodes being driven for alternate on and off periods with the glow mode electrodes being on when the main electrodes are off and the glow mode electrodes being off when the main electrodes are on.