0103 Age-Related Changes in Emotional Memory and Processing Depend on Slow-Wave and REM Sleep Microstructure

Abstract Introduction Aging is characterized by reduced slow-wave sleep (SWS) and relatively preserved Rapid Eye Movement (REM) sleep, but most prior research focus on the duration of these stages rather than their microstructural neurophysiological features. Although older adults typically remember positive information better and negative information less well, studies of sleep-based memory consolidation in aging have largely examined emotionally neutral material. The present study tested how slow-wave and REM microstructure change in aging, and whether age-related differences in emotional memory are moderated by specific microstructural features of SWS and REM sleep. Methods Fifty-nine healthy adults (ages 18-65) encoded scenes containing negative (e.g., a vicious-looking snake), positive (e.g., a cute kitten), or neutral objects (e.g., a chipmunk) superimposed on neutral backgrounds (e.g., an avenue). Post-encoding sleep was recorded using at-home polysomnography. The following morning, participants completed an old/new recognition task for each object and background. Finally, they viewed all encoding scenes again and rated their valence. Results Advancing age was associated with fewer (reduced count and density), weaker (lower amplitude), and shallower (less steep slope) slow waves during SWS. In contrast, REM amplitude and slope during REM sleep increased with age. Negative memory trade-offs (i.e., better memory for negative objects at the expense of paired neutral backgrounds) declined with age, but only when slow-wave counts were low. However, age was not correspondingly associated with increased positive memory trade-offs. Instead, older age was linked to perceiving all scenes more positively among individuals with more frequent slow waves, stronger slow waves, or steeper REMs. Conclusion Age-related changes in sleep microstructure are stage specific, with slow waves showing broad declines and REM events exhibiting selective increases in amplitude and slope. These patterns potentially reflect reduced homeostatic sleep regulation in late adulthood, which weakens slow-wave dynamics, while heightened REM activity may serve as a compensatory mechanism. Under conditions of reduced slow-wave quantity, older adults showed diminished prioritization of negative central details, which can limit their ability to prioritize salient and goal-relevant information. Conversely, preserved slow-wave quantity and quality, along with steeper REM activity, supported age-related positivity in affective interpretation, which may promote psychological resilience and well-being in later life. Support (if any)