Following the pioneering work of Schenk and Mahowald,¹ a robust association of idiopathic narcolepsy and rapid eye movement (REM) sleep behaviour disorder (RBD) has recently been confirmed, suggesting that around one third of patients with narcolepsy have concomitant RBD.² Although particularly severe cases with frequently occurring cataplexies and other associated symptoms of narcolepsy seem to be affected, the pathophysiological link between narcolepsy and RBD remains to be elucidated.

Contributing to this topic, in this issue, Mathis et al³(see p 427) report on a HLA DR2-negative patient who …