Systems, devices and methods for neurostimulation having a modulation of packets

A neurostimulation device, comprising:

• first and second electrodes;
• and
• a controller comprising a waveform generator configured to deliver a modulated electrical signal to a subject through the first and second electrodes, the modulated electrical signal comprising a plurality of packets of electrical pulses spaced apart from each other by a separation in time between adjacent packets of electrical pulses, each of the plurality of packets of electrical pulses comprising a plurality of electrical pulses spaced apart from each other by a separation in time between adjacent electrical pulses within each packet, each electrical pulse comprising a width in time and an amplitude in voltage;
• wherein the controller is configured to modulate the delivered electrical signal by varying the separation in time between adjacent ones of the plurality of packets of electrical pulses based on a time-varying modulation waveform and based on a target stimulus frequency by varying the separation in time between adjacent ones of the plurality of packets of electrical pulses in a sinusoidal modulation in a range between 100 microseconds and 100 milliseconds.