The first studies that measured orexin in cerebral spinal fluid (CSF) from humans occurred in 2000 and 2001, shortly after the discovery of orexin neuropeptide.37,50,51 Ripley et al. 2001, measured orexin in patients with narcolepsy and a wide range of neurological conditions.51 One of these conditions was craniocerebral trauma, now referred to as TBI. This evidence concerns the gene HCRT and narcolepsy.