Abstract: A method of applying an electrical signal transcranially includes the steps of generating a series of signal trains and applying the signal trains across the head of a subject, wherein each of the trains comprises a number of pulses and is separated from other trains by off periods, during which the signal is not applied. The signal trains are of such short duration that substantially no nerves within the subject's brain that receive the signal trains are demyelinized. In certain embodiments, the signal trains and the off periods are of irregular duration such that the activation of nerves of the brain by a signal is of a substantially continuous rate as the application of the signal train proceeds. The invention also includes particular characteristics of signals used to treat respective afflictions, including drug addictions and habituations, appetite disturbances, stress, insomnia, and pain.