Sleep and Emotional Memory: A Review of Current Findings and Application to a Clinical Population

Abstract

Purpose of review: The effect of sleep on the encoding and consolidation of emotional memory has been explored in multiple studies, however results are inconsistent. The purpose of this review is to synthesise current literature outlining the association between emotional memory and sleep, and to apply existing knowledge to a sleep disordered population. Recent findings: A sleep opportunity following encoding enhances the consolidation of emotional memories, however investigations into the contributing mechanisms have returned mixed results. The impact of sleep prior to encoding of emotional stimuli is less well known, however current studies suggest a bias towards negative over neutral and positive stimuli if sleep deprivation occurs prior to learning. Hormones such as cortisol and norepinephrine appear to play a key role in the enhancing effect seen for emotional memories after sleep. Neural activity during slow wave and rapid eye movement (REM) sleep may have a distinct but complementary role in this effect. Finally, populations with OSA may be at increased risk of mood disorder and poor emotional memory consolidation. Summary: Further studies should consider the complimentary processes of slow wave and REM sleep in the consolidation of emotional memory. Long term effects of untreated OSA on emotional memory also require further investigation.