Circadian and seasonal variation of migraine attacks in children.

Object.-To investigate the rhythmicity of migraine episodes without aura in a pediatric population. Methods.-Time of occurrence of 2517 migraine attacks in 115 children was recorded, by means of a diary, both by hourly and monthly intervals. Results.-A significant circadian variation, characterized by a peak in the afternoon (P <.001) and one in the early morning (P =.002) was found. A seasonal peak was also observed between November and January, while a nadir was observed in July. Conclusions.-The clustering of attacks in the morning and midday and in autumn-winter, with a minimum frequency in July, suggests that school activities may represent an important cause of migraine