 Generally, it seems external and bodily stimuli can be related to varying degrees to dream and sleep onset imagery (Nielsen 2017; Windt 2018; Windt et al. 2016). Some of these cases appear to fit the concept of illusion, as in when the sound of the alarm clock is experienced, in a dream, as a siren, or when blood pressure cuff inflation on the leg leads to dreams of wearing strange shoes (Windt 2018; for these and other examples, see Nielsen et al. 1995). In other cases, such as when blood pressure cuff stimulation on the leg prompts a dream of seeing someone else’s leg being run over, describing this as illusory misperception might be less straightforward.