Insomnia and circadian variation of attacks in episodic migraine

Objectives.-To assess the influence of insomnia on the 24-hour temporal pattern of migraine. Background.-Migraine attacks have been reported to occur in a harmonic (monophasic) or a biphasic 24-hour cyclic manner, and in some studies to have preponderance in the morning hours. The influence of insomnia on the circadian pattern has not been evaluated. Method.-Based on a previous study of the circadian variation in migraine, an explorative data analysis was made to compare the circadian pattern of insomnia-related migraine attacks to the circadian pattern of migraine attacks not related to insomnia. If the patients reported difficulties in failing asleep and/or maintaining sleep the night prior to the reported attack or the night the attack occurred, the attack was defined as insomnia-related. Relapses were not counted as distinctive attacks. Results.-Sixty-eight female migraineurs (mean SD age: 35.5 +/- 7.0) prospectively recorded 1869 migraine attacks. Five hundred-and-thirty-three attacks (29%) were insomnia-related. Insomnia-related attacks had a biphasic temporal pattern with one peak in the morning hours and one peak after noon. They had a preponderance in the morning hours compared to attacks not related to insomnia (t = 3.27, df = 62, P =.002). In 79% of attacks insomnia was experienced prior to the headache. Conclusions.-Episodic morning migraine is associated with insomnia. The cause and consequences of insomnia in migraine is not clarified, but sleep obviously protects against attacks rather than provokes them.