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Distinct Neural Dynamics in Emotional Memory Encoding between Insomnia and Healthy Sleepers

Poster Session E - Monday, March 9, 2026, 2:30 – 4:30 pm PDT, Fairview/Kitsilano Ballroom

Sen Mu¹ (), Shengzi Zeng^2,3, Danni Chen¹, Xiaoqing Hu^1,4; ¹The University of Hong Kong, ²Beth Israel Deaconess Medical Center, ³Harvard Medical School, ⁴HKU-Shenzhen Institute of Research and Innovation

Insomnia is associated with dysfunctional emotional memory processing, such as impaired dissipation of negative memories over time. However, the neural dynamics of emotional memory encoding that underlying the dysfunction in insomnia are not well understood. Elucidating these mechanisms could reveal novel interventions targeting maladaptive emotional memories to alleviate insomnia and negative affective outcomes. We collected electroencephalogram (EEG) data from 36 healthy controls (HC; 23 females, age, mean ± S.D., 24.42 ± 4.49) and 35 insomnia sleepers (IS; 23 females, age 24.55 ± 4.56), while they performed an emotional memory encoding task. During the task, participants learned 48 pseudoword–picture pairs (24 negative and 24 neutral pictures) across 4–6 learning-testing blocks. We first conducted a time-frequency analysis to characterize EEG oscillatory activity during encoding. We found that viewing negative emotional pictures elicited significantly higher power than neutral pictures across 1-18 Hz over fronto-central and parieto-occipital regions at 0–1000 ms window (pclusters < .05, corrected for multiple comparisons across time, frequency, and space) in HC while such a significant difference was absent in IS (pclusters > .05). To investigate this absence, we calculated the between-subject SD within the significant time-frequency-space cluster identified by the previous test, and found that IS demonstrated significantly higher between-subject variability in the 1–8 Hz band (300–800 ms post-picture cue; Fligner-Killeen test, p = .022), indicating greater heterogeneity in emotional memory encoding. Our findings indicate that emotional memory encoding in insomnia is marked by neurophysiological heterogeneity and insomnia may consist of distinct subtypes regarding the emotional memory encoding.

Topic Area: LONG-TERM MEMORY: Other