Effect of emotional and neutral declarative memory consolidation on sleep architecture

The relationship between emotional or neutral declarative memory consolidation and sleep architecture was investigated. Thirty university students (21 females) viewed negative, neutral, or positive pictures and rated their valence and arousal in the evening. Participants performed a recognition test 1 h later and then underwent overnight polysomnography. Their post-encoding sleep architecture was compared to a baseline night. Participants returned 6 days following encoding for a second recognition test. Results showed no group (Negative, Neutral, Positive) differences in recognition 1 h or 6 days following encoding. Stage 2 sleep spindle density decreased across all groups following encoding, and recognition after 6 days was positively correlated with Stage 2 sleep spindle density on both nights. There was no change in REM density in any of the groups. This is the first investigation into phasic sleep microarchitecture changes following emotional and neutral declarative learning. Future investigations may benefit from more salient emotional stimuli.