Fig. 3From: Neurobiology and sleep disorders in cluster headacheHypnograms from night 1 (top) and 2 (bottom) from a patient suffering nine spontaneous CH attacks (arrows) during recordings. As is seen, the attacks occur in stages W, REM, N2 and N3 at remarkably regular intervals. With permission from Barloese et al. 2014 (Wiley) [51]Back to article page