Cluster headache shows no association with rapid eye movement sleep

Background: The connection of cluster headache (CH) attacks with rapid eye movement (REM) sleep has been suggested by various studies, while other authors challenge this assumption. We performed serial polysomnography to determine the association of nocturnal CH attacks and sleep. Methods: Five patients diagnosed with CH (two with the episodic and three with the chronic subtype) were included and studied over four consecutive nights to evaluate connections between attacks onset and sleep stage. Results: Twenty typical CH attacks were reported. Thirteen of these attacks arose from sleep. Seven attacks were reported after waking in the morning or shortly before going to sleep. The beginnings of sleep-related attacks were distributed arbitrarily between different non-REM sleep stages. No association of CH attacks with REM or sleep disordered breathing was observed. Increased heart rate temporally associated with transition from one sleep state to another was observed before patients awoke with headache. Total sleep time, total wake time, arousal index and distribution of non-REM sleep stages were different between chronic and episodic CH. Conclusion: CH attacks are not associated with REM sleep. Brain regions involved in sleep stage transition might be involved in pathophysiology of CH. Differences in sleep characteristics between subgroups might indicate adaptation processes or underlying pathophysiology.