Improved subjective sleep quality in older adults by enhancing the GABAergic system in the sensorimotor cortex

Sleep disturbances affect nearly half of all adults aged 60 and above, reducing quality of life and contributing to various health issues. While pharmacological treatments enhancing GABAergic activity can improve sleep, they often have adverse side effects. Given that balance training has been shown to enhance GABAergic inhibition in the sensorimotor cortex, we hypothesized that it could serve as a non-pharmacological intervention to improve sleep quality in older adults. In this study, 36 adults aged 64 to 81 years either completed a three-month balance training programme or served as controls. Before and after the three months, all participants underwent behavioural and neurophysiological measurements. Following a significant group × time interaction with repeated-measures ANOVA, paired t tests revealed that the balance group experienced improved sleep quality assessed with the Pittsburgh Sleep Quality Index questionnaire. However, objective sleep parameters assessed with polysomnography remained unchanged. Neuroimaging revealed increased GABA levels in the sensorimotor cortex (magnetic resonance spectroscopy) and enhanced sensorimotor functional connectivity (functional magnetic resonance imaging). Although intracortical inhibition (transcranial magnetic stimulation) during balancing and sleep did not show significant group × time interactions, individuals with greater increases in inhibition during sleep reported larger improvements in sleep quality. Regression analyses indicated that greater increases in functional connectivity were associated with larger improvements in subjective sleep quality, whereas greater increases in GABA levels were associated with smaller improvements. These findings suggest that balance training improves subjective sleep quality in older adults, possibly by restoring the GABAergic system in the sensorimotor cortex, offering an accessible and non-pharmacological intervention for age-related sleep disturbances. KEY POINTS: Sleep disturbances are common in adults over 60, and medications that enhance GABAergic inhibition often cause unwanted side effects. Previous research suggests that balance training can strengthen GABAergic inhibition in the sensorimotor cortex. In this study, three months of balance training improved subjective sleep quality in older adults, while no changes were observed in objective sleep measures. These improvements may be driven by enhanced GABAergic inhibition in the sensorimotor cortex, as reflected by increased functional connectivity and intracortical inhibition, two functional markers of GABAergic activity. These findings highlight balance training as an accessible and multi-beneficial intervention to promote sleep health in older adults.