It has been demonstrated that cerebrospinal fluid (CSF) and plasma orexin-A levels are significantly lower in patients with PTSD than in healthy controls, and CSF orexin-A levels are strongly and negatively correlated with PTSD severity, as measured by the Clinician-Administered PTSD Scale, in patients with PTSD [70]. This evidence concerns the gene HCRT and post-traumatic stress disorder.