Headache in sleep apnea syndrome: epidemiology and pathophysiology.

This review investigates the relation between obstructive sleep apnea and sleep apnea headache, migraine and tension-type headache. Focus is made on studies from the general population with interviews conducted by a physician and obstructive sleep apnea confirmed by polysomnography. Obstructive sleep apnea syndrome is observed in 3% of the middle-aged population. The prevalence of sleep apnea headache in this population is 12%-18%, while morning headache with similar symptomatology as sleep apnea headache occur in 5%-8% of the general population. People with sleep apnea headache did have significantly more minutes below 90% oxygen saturation (23.1 min vs. 1.9 min, p = 0.002), higher level of average oxygen desaturation (5.9% vs. 4.5%, p < 0.001) and lower average of the lowest oxygen saturation (80.9% vs. 88.5%, p < 0.001) than people with morning headache. A comparison of those with obstructive sleep apnea with or without sleep apnea headache showed no significant differences. Thus, oxygen desaturation alone cannot explain the pathophysiology of sleep apnea headache. Obstructive sleep apnea and migraine, and obstructive sleep apnea and tension-type headache are not related in the general population. The cause of sleep apnea headache remains to be elucidated.