Incorporation of recent waking-life experiences in dreams correlates with frontal theta activity in REM sleep.

Jean-Baptiste Eichenlaub,Frederic Boy,Mark Blagrove,Penelope A Lewis,Emmanuel Maby,Matthew P Walker,Elaine Van Rijn,Josie E Malinowski,M Gareth Gaskell

doi:10.1093/scan/nsy041

Abstract

Rapid eye movement (REM) sleep and its main oscillatory feature, frontal theta, have been related to the processing of recent emotional memories. As memories constitute much of the source material for our dreams, we explored the link between REM frontal theta and the memory sources of dreaming, so as to elucidate the brain activities behind the formation of dream content. Twenty participants were woken for dream reports in REM and slow wave sleep (SWS) while monitored using electroencephalography. Eighteen participants reported at least one REM dream and 14 at least one SWS dream, and they, and independent judges, subsequently compared their dream reports with log records of their previous daily experiences. The number of references to recent waking-life experiences in REM dreams was positively correlated with frontal theta activity in the REM sleep period. No such correlation was observed for older memories, nor for SWS dreams. The emotional intensity of recent waking-life experiences incorporated into dreams was higher than the emotional intensity of experiences that were not incorporated. These results suggest that the formation of wakefulness-related dream content is associated with REM theta activity, and accords with theories that dreaming reflects emotional memory processing taking place in REM sleep.

Highlights

Rapid eye movement (REM) sleep and its main oscillatory feature, frontal theta, play a critical role in the processing of recent and emotional memories
As memories constitute much of the source material for our dreams, we explored the link between REM frontal theta and the memory sources of dreaming, so as to elucidate the brain activities behind the formation of dream content
This study aimed to explore the link between REM frontal theta activity and the references to recent waking-life experiences in REM dreams, given that $80% of awakenings from REM sleep are followed by a dream report (Nielsen, 2000)

Summary

Introduction

Rapid eye movement (REM) sleep and its main oscillatory feature, frontal theta, play a critical role in the processing of recent and emotional memories (for reviews, see Walker, 2009; Walker and van der Helm, 2009; Genzel et al, 2015; Hutchison and Rathore, 2015). Recent studies indicate that slow wave sleep (SWS) could play a complementary role in this processing (Cairney et al, 2015; Payne et al, 2015), compelling evidence supports the offline benefit of REM sleep for the processing of emotional memories (Wagner et al, 2001; Lara-Carrasco et al, 2009; Received: 10 November 2017; Revised: 5 May 2018; Accepted: 29 May 2018 VC The Author(s) (2018). The nature of the daily experiences incorporated into dreams has been explored, highlighting that emotional and personally significant experiences are preferentially incorporated (Cartwright et al, 1998b, 2006; Schredl, 2006; Propper et al, 2007; Malinowski and Horton, 2014)

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