HCRT and post-traumatic stress disorder: Figure 1 shows that orexin neuron activity was very high in normal-awakening rats, indicating a readiness for the transition from being asleep to awake. Activity was relatively low in the FS and PS groups that exhibited startled awakening, indicating that orexin neurons were not fully prepared for awakening at that moment. Clinical analyses showed that cerebrospinal fluid and plasma orexin-A concentrations were significantly lower in patients with PTSD compared with healthy control subjects (Strawn et al., 2010), which was consistent with the present results.