PhD Oral Exam - Loïc Barbaux, Health and Exercise Science

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

Sleep supports overall health and cognition, notably memory consolidation through NREM-related brain oscillations. Sleep architecture is disrupted by aging, with chronic insomnia further compounding these changes. Given its links to cognitive decline and adverse health outcomes, addressing chronic insomnia in older adults is critical for promoting healthy aging.

High insomnia prevalence in older adults contributes to widespread sedative-hypnotic use, yet its impact on sleep regulation remains unclear. We compared sleep architecture, EEG spectrum, and NREM brain oscillations related to memory consolidation across older adults with chronic insomnia, with and without chronic sedative-hypnotic use (benzodiazepines, BDZ, and benzodiazepine receptor agonists, BZRA), and good sleepers. Findings indicated that chronic BZD and BZRA use impairs sleep regulation at both macro- and micro levels, potentially mediating the association with cognitive decline in aging.

Cognitive behavioral therapy for insomnia (CBTi) is a non-pharmacological intervention that constitutes the first-line treatment for insomnia. This study assessed the combined impact of CBTi and sedative-hypnotic withdrawal on sleep and cognition in older adults with chronic insomnia. The combined intervention improved withdrawal success, reduced insomnia severity, and preserved sleep duration, while also enhancing subjective sleep quality. A concurrent reduction in sleep spindle density was observed. These findings highlight strategies for safer and more effective sedative-hypnotic discontinuation in aging populations.

Rocking bed stimulation represents a promising intervention to improve sleep and memory, although its long-term effects remain unclear. This study examined the impact of three consecutive nights of rocking apparatus stimulation in young good sleepers to replicate prior findings, intended for future application in older adults with insomnia. On the first night, rocking stimulation did not enhance sleep architecture, brain oscillations, or memory, likely due to suboptimal motion and noise-related disturbances. However, a second night rescued some effects, suggesting rapid habituation. These findings underscore the importance of refining stimulation parameters to optimize the potential benefits of rocking on sleep and memory.

This thesis presents new insights into pharmacological, behavioral, and rocking motion interventions, which may help design a comprehensive approach to enhancing sleep quality and cognitive health in aging populations.