Involuntary “what if” moments: Improbable simulations across the sleep-wake cycle and their relationship with anxiety

Improbable simulations, or spontaneous thoughts that consist of events that are unlikely to occur in waking life, are presumably common experiences during both periods of waking and dreaming. Yet, despite anecdotes of involuntarily simulating experiences like driving off the road, throwing your cellphone off a bridge, or screaming in a crowded room, the empirical work on this topic has been quite limited. Here we attempt to shed some foundational light on such improbable simulations by exploring their perceived occurrence and relation to sense of agency and intolerance of uncertainty throughout the sleep/wake cycle. Participants (N=100) indicated their perceived frequency and affective valence of improbable simulations related to certain themes (personal, social, and nature) across waking and dreaming states. Although participants perceived experiencing improbable simulations more often while awake, the common themes and valence of improbable simulations did not differ across periods of waking and dreaming - that is, participants were most likely to simulate personal events in both states, and social simulations were the most positive theme in both states. Critically, all themes in waking were positively correlated with intolerance of uncertainty, a characteristic of various anxiety disorders, while this relationship was only observed for personal simulations in dreaming states. However, no such relation was observed for sense of agency for any theme across waking and dreaming states. Our findings thus provide insights on the general nature of improbable simulations across both wake and sleep, as well as their relation to anxiety characteristics.