Changes of biological rhythms in primary headache syndromes.

The circadian periodicity of some endocrine (PRL, cortisol, GH) and vegetative (oral temperature, blood pressure) functions has been studied in cluster headache, common migraine, atypical facial pain, and "mixed" headache. Changes in several biological rhythms have been found not only in cluster headache (CH) but also in other kinds of headache. Although a great individual variability of rhythometric changes has been observed, particularly in CH, the dysrhythmic condition seems to be more evident in chronic than in episodic CH. The clinical and chronobiological effects of lithium administration and of a short-term sleep deprivation have been studied in CH.