The activation in the trigeminal system, however, does not seem to provoke CH pain attacks or the typical sensations that commonly accompany trigeminal activation.13 This connection has been previously observed after injection of the neuropeptide orexin B into the posterior hypothalamic region of the rat, which increased spontaneous activity in the caudal trigeminal nucleus (with discharges persisting for several minutes) and heightened responses in the nucleus to dural stimulation and noxious thermal stimulation of the face.15 Here, HCRT is linked to cyclic hematopoiesis.