The Effect of a Slowly Rocking Bed on Sleep

Ximena Omlin,Alexander Malafeev,Antonio Fernandez Guerrero,Peter Achermann,Jelena Skorucak,Francesco Crivelli,Monika Näf,Lorenz Heinicke,Robert Riener

doi:10.1038/s41598-018-19880-3

Abstract

Rocking movements appear to affect human sleep. Recent research suggested a facilitated transition from wake to sleep and a boosting of slow oscillations and sleep spindles due to lateral rocking movements during an afternoon nap. This study aimed at investigating the effect of vestibular stimulation on sleep onset, nocturnal sleep and its potential to increase sleep spindles and slow waves, which could influence memory performance. Polysomnography was recorded in 18 males (age: 20–28 years) during three nights: movement until sleep onset (C1), movement for 2 hours (C2), and one baseline (B) without motion. Sleep dependent changes in memory performance were assessed with a word-pair learning task. Although subjects preferred nights with vestibular stimulation, a facilitated sleep onset or a boost in slow oscillations was not observed. N2 sleep and the total number of sleep spindles increased during the 2 h with vestibular stimulation (C2) but not over the entire night. Memory performance increased over night but did not differ between conditions. The lack of an effect might be due to the already high sleep efficiency (96%) and sleep quality of our subjects during baseline. Nocturnal sleep in good sleepers might not benefit from the potential facilitating effects of vestibular stimulation.

Highlights

Restorative sleep represents a key factor for well-being and day-time functioning, achieving it often poses a problem
Sleep latency, slow wave sleep (SWS) latency and REM sleep latency were comparable among the conditions and did not reveal significant differences
We found our effect sizes to be small (Cohen’s d for baseline compared to C1 and C2; sleep latency: 0.24 (C1), 0.21 (C2); N1: 0.29 (C1), 0.23 (C2); N2: 0.01 (C1), 0.18 (C2); number of spindles: 0.08 (C1), 0.18 (C2)) and not within the range of the large effect sizes reported for vestibular stimulation during an afternoon nap[14]

Summary

Introduction

Restorative sleep represents a key factor for well-being and day-time functioning, achieving it often poses a problem. The aim of this study was, to investigate the effect of rocking movements on sleep onset and sleep It was studied whether vestibular stimulation mainly affects sleep onset or if a cumulative effect would be observed with longer stimulation duration. It was investigated if vestibular stimulation has the potential to increase sleep spindles and SO, which might influence memory performance assessed by a word pair task. In previous studies movement parameters were set by the experimenter and only linear lateral swing movements had been applied[14,15] It is, not clear, which kind of movement (translations or rotations, amplitudes, frequencies) could promote relaxation in an optimal way and might facilitate sleep onset and influence sleep quality. If the effect of vestibular stimulation is related to relaxation, the greatest effect would be expected with a movement perceived as most relaxing by the participants

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