“…In retrospective questionnaire studies, up to 62% of migraine patients reported that psychosocial stress was an important trigger factor for their attacks (Van den Berg et al, 1987;Robbins, 1994;Zivadinov et al, 2003), but patients have a tendency to overestimate stress on retrospective measures (Wittrock and Foraker, 2001). In crosssectional studies, migraine patients were found to have elevated plasma levels of cortisol, an indicator for stress, both outside a migraine attack compared to healthy volunteers (Ziegler et al, 1979) and during attacks compared to the inter-ictal phase (van Hilten et al, 1991). Stress-provocation studies, involving mental and physical stressors, have suggested sympathetic and parasympathetic changes in migraine patients outside attacks compared to healthy volunteers (Takeshima et al, 1987;Hassinger et al, 1999;Shechter et al, 2002;Avnon et al, 2004).…”