Scammell and Winrow (2011) demonstrated that OXR2 or non-competitive orexins inhibitors were effective in treating insomnia, suggesting that OXR2 may play a more important role. Irving observed an increase in the OXR1 gene expression in rats with cerebral ischemia (Irving et al., 2002), while OXR2 gene expression did not change significantly. Here, OXR1 is linked to brain ischemia.