The present invention relates to a stimulation system, comprising a lead configured to contact neural tissue and an implantable pulse generator configured to deliver successive non-regular electrical pulse trains including non-regular inter-pulse intervals which are linearly cyclically ramped over time to the lead, wherein the successive non-regular electrical pulse trains have an instantaneous change so that a final inter-pulse interval in an earlier train is larger than a first inter-pulse interval in an immediately subsequent train and wherein each non-regular electrical pulse train includes a singlet pulse spaced apart by progressively increasing inter-pulse intervals which decrease in frequency over time from about 140 Hz to 40 Hz.
