Adolescent sleep: Learning, memory, and mental wellbeing

This thesis explores the relationship between adolescent sleep, learning, memory, affect, and mental health. In Chapter 2 (N = 11), multi-night sleep recordings showed 13-16-year-olds were sleep restricted during school nights compared to free nights. At-home polysomnography found slow-wave sleep was relatively preserved despite sleep restriction. In Chapter 3 (N = 45), spindles during a pre-encoding nap were positively correlated with overnight improvements in lexical integration. Chapters 2 and 3 did not find slow-wave sleep to be associated with behavioural performance, despite predictions made by the synaptic homeostasis hypothesis (Tononi & Cirelli, 2003, 2006, 2014). In relation to affect and mental health, two online studies were conducted. Chapter 4 (N = 247) found good sleepers on the PSQI had higher neutral than positive memory, whilst the opposite was seen for poorer sleepers at the one-year follow-up, not during lockdowns. Chapter 5 found reactivity toward, or recognition of, emotional stimuli did not significantly mediate the relationship between sleep and mental health, contrary to Goldstein and Walker’s (2014) framework, but was mediated by lower thought control ability supporting Harrington & Cairney’s (2021) model. High positive affect mediated the relationship between better sleep and lower depression for the younger (N = 118) but not older adolescents (N = 136). Lastly, in Chapter 6 (N = 7,167) NHS CAMHS patients with an ADHD diagnosis were significantly more likely to be prescribed sleep medication than patients with most other mental health diagnoses (except psychosis and autism or learning disability). Longer service use was also associated with greater reporting of sleep issues and prescription of sleep medication. Together, this thesis demonstrates the importance of sleep for adolescents’ learning, memory, and mental wellbeing. This is particularly important, as some adolescents may need sleep interventions to benefit their education (e.g., GCSEs, A-Levels, University) and mental health. However, Chapter 6 suggests some interventions (i.e., sleep medication) may not be accessed equally.