1 Department of Neuroscience, Faculty of Medicine, University of Geneva, Geneva, Switzerland.
2 Department of Health, Kinesiology and Applied Physiology, Concordia University, Montreal, Canada.
3 Centre de Recherche de l'institut Universitaire de Gériatrie de Montréal, CIUSSS Centre-Sud-de-l'ile-de-Montréal, Montreal, Canada.
4 Sleep & Circadian Research Group, Woolcock Institute of Medical Research, Macquarie University, Sydney, New South Wales, Australia.
5 Brain and Mind Centre, School of Psychology, The University of Sydney, Sydney, New South Wales, Australia.
6 Swiss Center for Affective Science, Campus Biotech, Geneva, Switzerland.
7 Center for Sleep Medicine, Geneva University Hospital, Geneva, Switzerland.

Specific brain oscillations can be manipulated during sleep to improve sleep quality and memory performance. We previously demonstrated that continuous rocking stimulation (0.25 Hz, lateral movement) applied to good sleepers during sleep enhanced stable deep sleep, boosted NREM oscillations (spindles and slow waves) and memory consolidation. Here, we investigated whether nocturnal rocking could benefit individuals suffering from sleep difficulties. We recruited 16 young adults with subjective difficulties initiating and/or maintaining sleep and who presented with objective poor sleep quality. After a habituation night, each participant spent two nights of sleep at the laboratory, one rocking and one stationary, during which we assessed sleep and declarative memory consolidation. We found that a whole night of gentle rocking in individuals with poor sleep decreased sleep fragmentation, time spent awake and in light sleep (N1), with an associated increase in objective sleep efficiency and subjective sleep quality. Additionally, we replicated the neural entrainment or synchronising effect of the rocking motion, yielding a boost in NREM fast spindles and slow oscillations. Yet, these changes in sleep did not modulate overnight memory performance. By alleviating some difficulties encountered in this population of poor sleepers, these findings provide preliminary evidence that rocking may represent an alternative or complementary intervention for the management of some forms of chronic insomnia.