Study Objectives Motor memory consolidation is a process by which newly acquired skills become stable over time in the absence of practice. Sleep facilitates consolidation, yet it remains unknown whether sleep-dependent consolidation is intact in people with Parkinson′s disease (PD). Here, we investigated whether a post-learning nap - as compared to wakefulness - improves motor memory consolidation in PD. Methods Thirty-two people with PD and 32 healthy older adults (HOA) learned a finger-tapping sequence task before being randomized to a nap or wake intervention. Consolidation was measured as the change in performance between pre- and post-intervention and at 24-hours retention. Automaticity was measured with a dual-task assessed post-intervention and at retention. Sleep architecture and electrophysiological markers of plasticity were extracted from the experimental nap to assess their association with performance changes. Results Behavioural results provided weak evidence for equivalent benefit of sleep-dependent consolidation over wakefulness in both PD and HOA, and no difference of intervention effects between groups. Napping did not affect dual-task costs in PD or HOA. Results suggested positive associations between performance improvements and slow wave density, amplitude, slope, and spindle amplitude in PD and not in HOA. Conclusions A post-learning nap had similar effects in PD and HOA, yet the evidence remains inconclusive. Further, napping did not have a beneficial effect over wake in either group. In PD, sleep markers of plasticity were associated to performance improvements, suggesting that equivalent performance output between HOA and PD may be achieved using different consolidation mechanisms.

The authors have declared no competing interest.

NCT04144283

Funding for this study was provided by the Funds Malou Malou & Perano, managed by the King Baudouin Foundation (2019-J4121350-212854) and Internal Funds KU Leuven (STG/21/035). Moran Gilat was supported by a Marie-Skłodowska-Curie Action Postdoctoral Fellowship (TARGET-SLEEP, 838576). Letizia Micca is supported by a FWO PhD Fellowship (SLEEP ON IT, 11PQB24N). Judith Nicolas was funded by The Fondation Pour la Recherche Médicale (ARF202309017485). The authors would like to sincerely thank all the participants for their efforts. We also like to thank the staff at the Centre for Sleep Monitoring of UZ Leuven, Tine Wouters, Charlotte Moris and the master thesis students of Rehabilitation Sciences at KU Leuven for their assistance with data collection.

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The protocol was in accordance with the declaration of Helsinki and the World Medical Association, 2013 and was approved by the Medical Ethical Committee Research UZ / KU Leuven (S61792). All participants provided written informed consent prior to study related procedures.

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