Cerebrospinal fluid hypocretin levels are normal in idiopathic REM sleep behaviour disorder.

Background: Rapid eye movement (REM) sleep behaviour disorder (RBD) is a common sleep disorder that can be associated with a number of neurodegenerative conditions as well as with narcolepsy. Current diagnostic criteria require overnight polysomnography, and there are no other biomarkers available. The control of REM sleep is complex with a putative on/off switch within the brainstem activated, amongst other things, by hypocretinergic pathways from the lateral hypothalamus. Methods: Cerebrospinal fluid hypocretin levels were measured in five patients with idiopathic RBD. Results: Hypocretin levels were between 254 and 450 pg/ml and therefore within the normal range of >100 pg/ml. Conclusion: Hypocretin levels in patients with idiopathic RBD are normal. [ABSTRACT FROM AUTHOR]