Sleep Architecture Disruption and Cognitive Decline Risk Among Adults with Obstructive Sleep Apnoea in Calabar, South South Nigeria

Background: Obstructive sleep apnoea disrupts sleep architecture through repeated arousal events, suppressing slow-wave and rapid eye movement sleep stages critical for cognitive consolidation and neural repair. Evidence linking obstructive sleep apnoea to progressive cognitive impairment is accumulating internationally, yet Nigerian polysomnography and neurophysiological data in this domain are negligible. Objectives: This study aims to characterise polysomnographic sleep architecture parameters, including apnoea-hypopnoea index, oxygen desaturation index, and rapid eye movement sleep duration, among adults with obstructive sleep apnoea at the University of Calabar Teaching Hospital, and to assess their relationships with neuropsychological performance on attention, memory, and executive function tests. Methods: Forty adults with polysomnography-confirmed obstructive sleep apnoea and twenty controls with normal polysomnography will be recruited. Full overnight polysomnography will be reviewed for sleep staging and respiratory event indices. The Montreal Cognitive Assessment and Cambridge Neuropsychological Test Automated Battery subtests will assess cognition. Partial correlation controlling for age, education, and body mass index will test polysomnographic-cognitive associations. Expected Outcomes: Greater apnoea severity, higher oxygen desaturation index, and reduced rapid eye movement proportion are expected to independently predict poorer neuropsychological performance. Conclusion: Findings will establish the cognitive physiology burden of obstructive sleep apnoea in the South South zone and reinforce the need for polysomnography access in Nigerian tertiary hospitals. Keywords: obstructive sleep apnoea, sleep architecture, cognitive decline, polysomnography, Calabar.