Chronobiological correlates of headache: three decades on.

In 1983 an international symposium entitled "Chronobiological Correlates of Headache" was held in Capri. This meeting provided an opportunity to debate new and stimulating aspects of headache, in particular the temporal pattern of headache and the periodicity of the underlying biological and environmental phenomena. Giuseppe Nappi presented his dyschronic hypothesis of primary headaches, which was based on the observation that these conditions involve not only a dysfunction in pain control systems, but also a vulnerability of the rhythmic physiological organization of the central nervous system. He suggested that the hypothalamus played a key role in this vulnerability. Several decades on, thanks to the advent of new technologies (functional neuroimaging and neurophysiological studies), this hypothesis has been supported by scientific data.