HCRT and REM sleep behavior disorder: Moreover, no significant difference in CSF orexin levels between the three groups was demonstrated, despite Unified Parkinson's Disease Rating Scale (UPDRS-III) scores being significantly higher in the PD with RBD and PD without RBD groups and REM sleep behavior disorder questionnaire (RBDQ-HK) scores significantly higher in RBD, perhaps suggesting that orexin levels may not be a sensitive marker for motor severity and sleep behaviours [56].