Electrical stimulation has been used as a sort of defibrillator of consciousness, rousing a victim of traumatic brain injury to at least partial awareness, after years in a coma. The procedure, termed deep brain stimulation, has also been used to treat Parkinson's disease and has shown some promise for use in epilepsy, cluster headaches and treatment-resistant depression. But new research shows that the even, equally spaced electrical pulses typically used in the procedure now are not necessarily the most effective.