034 Dreaming as Constructive Episodic Future Simulation

Abstract

Abstract Introduction Memories of the past help us respond to similar situations in the future. The “episodic future simulation” hypothesis proposes that waking thought combines fragments of various past episodes into imagined simulations of events that may occur in the future. We asked whether this framework from waking cognitive neuroscience may be useful for understanding the function of sleep and dreaming. We hypothesized that participants would commonly identify future events as the source of a dream. Further, we expected future-oriented dreams to draw on multiple different waking memories, with fragments of past experience combined into novel scenarios relevant to anticipated events in participants’ personal futures. Methods N=48 students spent the night in the laboratory with polysomnographic recording. During the night, participants were awakened up to 13 times to report on their experiences during sleep onset, REM and NREM sleep. The following morning, participants identified and described waking life sources for each dream reported the previous evening. A total of N=481 reports were analyzed. Results While dreams were most commonly traced to past memory (53.5% of reports), more than a quarter (25.7%) were related to specific impending future events. Nearly half of reports with a waking source were traced to multiple different sources (49.7%). Over a third of dreams with a future event source were additionally related to one or more specific past episodic memories (37.4% of all reports with a future episodic source). Future-oriented dreams became proportionally more common later in the night. Conclusion First, we confirm prior reports that dreams not only reflect past memory, but also anticipate probable future events. Furthermore, these data provide a novel description of how future-oriented dreams draw simultaneously from multiple waking-life sources, utilizing fragments of past experience to construct novel scenarios anticipating future events. The proportional increase of future-oriented dreams later in the night may be driven by temporal proximity to the events of the following day. While these dreams rarely depict future events realistically, the activation and recombination of future-relevant memory fragments may nonetheless serve an adaptive function. Support (if any) This work was supported by Bursaries award 83/12 from the BIAL Foundation.