Sleep disordered breathing (SDB) may trigger cluster headaches (CH), according to researchers from the department of neurology, University of Michigan, US (Neurology 2000;54:2302).
They evaluated 25 adults with CH in a sleep laboratory and found that 80 per cent showed some signs of obstructive sleep apnoea. They say that, although there is no obvious explanation for how SDB could cause CH, several features of the disorder, including hypoxaemia and abrupt changes in sympathetic tone, could trigger vascular changes thought to underlie cluster headache.
CH is particularly likely to occur during sleep and the researchers also found an association between the extent of hypoxemia and timing of CH occuring during the first half of the night.