Cluster headache patients have normal circadian and sleep time autonomic nervous system function

Cluster headache (CH) is a rare form of primary headache of neurovascular origin causing severe pain attacks associated with autonomic changes. Attacks are more likely to occur during sleep. Time-frequency decomposition (TFD) of instantaneous heart rate variability (HRV) is widely accepted as a non-invasive tool of investigation of autonomic nervous function and was applied in the present study. Our goal was to estimate the autonomic features of CH patients and their connection to sleep. The study included 20 subjects belonging to 3 groups: (a) CH (active headache attacks, N=7); (b) Normal control (C, N=6); (c) patients with CH during a quiet period (QP, N=7). The study revealed similar circadian behaviour of all HRV variables and of the HR in all groups indicating normal changes in central autonomic function between daytime and sleep in CH. Increased overall VLF power in CH compared to normal subjects suggests increased vasomotor activity during active headache periods only