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Sleep and memory studies often focus on overnight rather than longterm memory changes, traditionally associating overnight memory change (OMC) with sleep architecture and sleep patterns such as spindles. In addition, (para)sympathetic innervation has been associated with OMC after a daytime nap using heart rate variability (HRV). In this study we investigated overnight and longterm performance changes for procedural memory and evaluated associations with sleep architecture, spindle activity (SpA) and HRV measures (RR interval [RRI], standard deviation of RR intervals [SDNN], as well as spectral power for low [LF] and high frequencies [HF]). All participants (N = 20, Mage = 23.40 2.78 years) were trained on a mirrortracing task and completed a control (normal vision) and learning (mirrored vision) condition. Performance was evaluated after training (R1), after a fullnight sleep (R2) and 7 days thereafter (R3). Overnight changes (R2R1) indicated significantly higher accuracy after sleep, whereas a significant longterm (R3R2) improvement was only observed for tracing speed. Sleep architecture measures were not associated with OMC after correcting for multiple comparisons. However, individual SpA change from the control to the learning night indicated that only “SpA enhancers” exhibited overnight improvements for accuracy and longterm improvements for speed. HRV analyses revealed that lower SDNN and LF power was associated with better OMC for the procedural speed measure. Altogether, this study indicates that overnight improvement for procedural memory is specific for spindle enhancers, and is associated with HRV during sleep following procedural learning. P15370 W1233G17 (VLID)4373764