HCRT and Parkinson disease: • T. Ogawa, Y. Kajiyama, H. Ishido, S. Chiba, G.S. Revankar, T. Nakano, S. Taniguchi, T. Kanbayashi, K. Ikenaka, and H. Mochizuki, Decreased cerebrospinal fluid orexin levels not associated with clinical sleep disturbance in Parkinson’s disease: A retrospective study.