Specific Aim 3: Test the hypothesis that administration of trazodone, in patients with cervical spinal cord injury and central SDB will decrease respiratory related arousals and central apnea index, and the propensity to develop central apnea, compared to placebo. To accomplish this aim, the investigators will test the acute effect of trazodone on respiratory related arousals and central sleep apnea, and the chronic effect on central apnea indices and the CO2 reserve.