Sleep and headache: a bidirectional relationship.

Sleep and pain perception are two phylogenetically well-conserved functions, strictly influenced by environmental and psychological factors, and are able to interact reciprocally both in physiological and pathological situations. Sleep and head-pain perception share the involvement of several structures, such as the thalamus, the hypothalamus and brainstem nuclei, including the locus coeruleus and raphe nuclei. There ais clinical evidence indicating that sleep disorders can precede the appearance of certain headaches and that head pain, especially when frequent, can, in turn, affect sleep quality. In the present work the anatomy, physiology and pathology of sleep and head-pain perception will be reviewed with the aim of highlighting the points of contact and possible unifying treatment strategies.