The role of sleep in migraine attacks.

Migraine attacks may be precipitated by sleep deprivation or excessive sleep and sleep is also associated with relief of migraine attacks. In view of this variable relationship we studied the records of 159 consecutive outpatients of our Headache Unit. In 121 records there was reference to sleep involvement, in 55% by a single form and in 45% by more than one form. When only one form was related, relief was most common (70%). 30% of that group of patients had the migraine attack precipitated by sleep, 24% by deprivation and 6% by sleep excess. When the effects of sleep were multiple, these effects were as expected logically in 65%: "in accordance" group (e.g attack precipitated by sleep deprivation and relieved by sleep onset. In a second group, ("conflicting") where the involvement was not logical, there were three different combinations of sleep involvement, possibly due to more than one pathophysiological mechanism.