We all know what sleep deprivation does to us. We’re unable to pay attention. We’re often cold or hot. We can’t think straight, we start doing very strange things (you would not BELIEVE the crazy dances I’ve made up…), and of course, we’re really, really tired. But why do these symptoms happening? What’s going on in the brain during sleep deprivation to explain this behavior? Well, in part, it might be changes in your D2 receptors.