Background: Morning headaches are often ascribed to patients with sleep apnea syndrome (SAS) but the etiology of headaches in SAS is unclear. Given the relationship between oxygen and other headache syndromes, nocturnal hypoxia might be one factor contributing to headaches in SAS.
Methods: All subjects 18-80 years of age who were determined to have SAS and who underwent a continuous positive airway pressure trial in our sleep laboratory between March 1, 1997 and March 18, 1998 were considered for inclusion. Subjects were grouped according to whether they endorsed that waking with headaches is a problem for them. Polysomnography and standardized questionnaires were used to test the main hypothesis that patients with SAS and headaches would spend more time at lower oxyhemoglobin levels than those SAS patients without headache.
Results: Headache and non-headache patients did not differ in the percentage of time spent with an oxygen saturation less than 90%, either in total sleep time or in rapid eye movement sleep (REM). The headache patients were more likely to be female and spend a lower percentage of time in REM sleep. The REM sleep difference was not accounted for by the use of REM suppressing medications or by depression (as measured by the Zung scale).
Conclusions: These data do not support the hypothesis that the duration of nocturnal hypoxemia relates to headache complaints in patients with SAS. The lower REM sleep percentage and higher variability in REM apnea index among the headache patients warrants further investigation.