From his experience with animal studies, Panksepp posits that there are several ingrained emotional operating systems in the brain, including the systems for seeking behavior, fear, panic, and rage. Along with these, there is a sophisticated special-purpose social emotional system that may mediate sexual lust, maternal care, and play. These inherited circuits support specific functions. For example, the seeking circuits are engaged during interest, curiosity, and eager anticipation. The rage circuits allow reactions of aggression or irritation to threats of a physical or psychological nature. Fear and anxiety circuits help to protect the animal from physical harm. All these circuits are grounded in control systems that also control the sleep/waking cycle. In this regard, Panksepp’s proposal about a function of sleep/dreams is interesting. He suggests that "perhaps what is now the REM state [of sleep] was the original form of waking consciousness in early brain evolution, when emotionality was more important than reason in the competition for resources" (p. 128). In short, this form of waking consciousness might have been later suppressed in order for higher brain evolution to proceed.