Fragmented Sleep, Learning and Memory: Investigating Overnight Memory Consolidation in Paediatric Sleep Disordered Breathing

Abstract

Sleep Disordered Breathing (SDB) is a commonly diagnosed sleep disorder in children adversely impacting functioning in a variety of ways: physiological (blood pressure regulation, cardiac function, cerebral oxygenation, inflammatory cascade activations) behavioural (excessive daytime sleepiness, hyperactivity, poor concentration) and neurocognitive (verbal IQ, attention, executive function). However, little is known about the neurocognitive domain of memory consolidation in this clinical population. This is important because healthy developmental progression relies on effective learning and remembering of new information and skills. The aims of this thesis were to: (i) determine the current state of knowledge regarding neurocognitive outcomes for children with SDB, including memory consolidation, (ii) assess overnight consolidation of declarative and non-declarative memory in preschool and school age children, and (iii) explore the relationship between memory consolidation and specific sleep parameters (sleep spindles and slow wave oscillations). Four studies were conducted: a systematic review with meta-analysis and three empirical studies. Overall, to our knowledge, this research was the first to assess overnight memory consolidation in the preschool SDB population and to investigate the relationship between memory consolidation outcomes and direct measures of sleep spindles and slow wave power. Taken together, our studies provide evidence of different types of cognitive deficits in preschool and school aged children with SDB. While learning and memory consolidation was found disrupted in school-aged children, only attention but not learning and memory were disrupted in preschool children with SDB. This pattern of findings raises possibilities that SDB may have a cumulative effect on memory consolidation and/or that learning and memory deficits emerge as cognitive and physiological systems reach maturity.