An apparatus for stimulating a brain (3B) of a person (2) comprising a detector (10) for detecting an induced or a spontaneous physiological signal generated by the brain (3B), a control unit (12) being connected to said detector (10) for comparing the detected physiological signal with a criterion to determine an optimal setting of a variable signal parameter, a first signal generator (8) for applying an electrical stimulation signal (EES) to said person (2) and/or at least one second signal generator (9) for applying a sensory stimulation signal (SSS) to a sensory organ (3A) of said person (2), wherein a signal parameter of the stimulation signals (ESS, SSS) are adjusted to the determined optimal setting of said signal parameter.