Whole-night gentle rocking improves sleep in poor sleepers with insomnia complaints.

Abstract

Specific brain oscillations can be manipulated during sleep to improve sleep quality and memory performance. We previously demonstrated that continuous rocking stimulation (0.25Hz, 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 sixteen young adults with subjective difficulties initiating and/or maintaining sleep and who presented with objective poor sleep quality. 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 synchronizing 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 (e.g., sleep maintenance and poor self-reported sleep), these findings provide preliminary evidence that rocking may represent an alternative or complementary intervention for the management of some forms of chronic insomnia. STATEMENT OF SIGNIFICANCEHere, we demonstrate that a gentle and continuous rhythmic rocking stimulation applied during a whole night improves sleep in young adults with sleep complaints and objective poor sleep quality. Rocking, compared to a normal stationary condition, promoted sleep maintenance and sleep efficiency with a parallel improvement in subjective sleep quality. As we previously found in healthy controls, the rocking stimulation had a mechanistic influence over the synchronisation of sleep oscillations in these individuals with insomnia complaints. These findings may be relevant for the development of non-pharmacological interventions in similar populations with insomnia complaints and poor sleep, including older adults, and clinical populations with neurological, psychiatric, or somatic conditions.