While the most prominent role of orexin relates to wakefulness, arousal and sleep (Chemelli et al., 1999), orexins also have well studied effects on feeding behaviour (Sakurai et al., 1998), physical activity (Hagan et al., 1999; Kotz et al., 2002), reward, motivation (Harris et al., 2005), stress (Samson et al., 2002) and anxiety (Suzuki et al., 2005). The gene discussed is HCRT; the disease is Anxiety.