A method of treating a patient having neurologic function affected by Parkinson's disease is provided. The method includes providing a patient having neurologic function affected by Parkinson's disease. The method further includes delivering electromagnetic radiation noninvasively through the scalp and the skull of the patient to at least one portion of the brain of the patient. The light energy has a wavelength in the visible to near-infrared wavelength range, and the wavelength, power density, and amount of the light energy delivered to the at least one portion of the brain are sufficient to reduce the severity of symptoms of Parkinson's disease in the patient.