Neurostimulation is delivered to one or more predetermined locations on or within a patient in order to treat effects of sleep apnea by modulating autonomic nervous activity. Delivery of neurostimulation at predetermined locations can decrease sympathetic nervous activity and/or increase parasympathetic nervous activity, countering the increased intrinsic sympathetic activity associated with apnea-arousal cycles. In some embodiments, neurostimulation is delivered to the spinal cord of the patient via an implanted electrode. In other embodiments, neurostimulation is delivered transcutaneously to the spinal cord or other locations via electrodes located on the surface of the patient. In some embodiments, delivery of neurostimulation is initiated or modified in response to detection of apneas.