We read with great interest the paper by Engstrøm et al. (2013) “
Sleep quality, arousal and pain thresholds in migraineurs: a blinded controlled polysomnographic study” [
1]. We appreciated the methodology of the study, nevertheless we believe that the hypothesis formulated by the Authors in their conclusion deserves further comments.
Discussion: alternative hypothesis
On the other hand, CAP modifications similar to those described in Migraineurs have been reported in normal subjects following sleep deprivation. Poryazova et al. (2011) [
6] investigated the regulation NREM sleep in normal subject and narcolepsy / cataplexy patients before and after sleep deprivation. This study [
6] demonstrated that: 1) patients with impaired arousability (narcolepsy patients) have lower CAP rate that controls; and 2) sleep deprivation induces a reduction of CAP rate, which, in normal subjects after deprivation, reached values similar to those reported in our study for Migraineurs.
Whatever the interpretation, we believe that these data, taken together, suggest that Migraine is a condition in which an impairment of arousal responses occurs. As suggested by Borsook et al. (2012), Migraine is associated with alterations in normal homeostatic mechanisms (e.g., altered sleep, abnormal autonomic function). When stressors become frequent and/or severe, allostatic responses may be dysregulated and become maladaptive (“allostatic load”). Such allostatic load, in turn, may alter brain responses to stressors; therefore, behavior and systemic physiology are altered in ways that can, in a vicious cycle, lead to further allostatic load [
7]. In this sense, arousals during sleep must be considered as an homeostatic, adaptive response, rather than a ‘pathologic’, disruptive phenomenon, which can be detrimental for sleep. The impaired arousability during sleep, seen in this view, is part of a more general decreased ability of Migraineurs to process incoming stimuli.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
CV: data analysis and interpretation, manuscript drafting and revision, final approval of the version to be published. ET: data analysis and interpretation, manuscript drafting and revision, final approval of the version to be published. AL: data analysis and interpretation, manuscript drafting and revision, final approval of the version to be published. SM: data analysis and interpretation, manuscript drafting and revision, final approval of the version to be published. GDM: data analysis and interpretation, manuscript drafting and revision, final approval of the version to be published. All authors read and approved the final manuscript.