Systems of and methods for stimulation of neurological tissue that may generate stimulation trains with temporal patterns of stimulation is shown and disclosed herein. The temporal patterns of stimulation may include intervals between electrical pulses (the inter-pulse intervals) that change or vary over time. Compared to conventional continuous, high rate pulse trains having regular (i.e., constant) inter-pulse intervals, the non-regular (i.e., not constant) pulse patterns or trains that embody features of the invention may provide a lower average frequency.