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Poor sleep hygiene in adolescence is associated with disrupted encoding and consolidation of newly learned words
Poster Session C, Saturday, September 13, 11:00 am - 12:30 pm, Field House
Rebecca Crowley1, Jessie Ricketts1, Lisa Henderson2, Gareth Gaskell2, Jakke Tamminen1; 1Royal Holloway, University of London, 2University of York
Sleep supports memory by restoring hippocampal encoding capacity after wakefulness (Cirelli & Tononi, 2020) and by redistributing newly acquired information from the hippocampus to long-term neocortical memory stores during memory consolidation (Klinzing et al., 2019). Both functions of sleep facilitate word learning. Sleep before word learning leads to better memory for the words (March et al., 2023). Sleep after word learning allows for lexicalisation whereby new words form integrated networks with similar words in the mental dictionary (Davis & Gaskell, 2009). While the impact of sleep on word learning is well documented in adults and young children, little is known about these mechanisms in adolescence, despite adolescence being a developmental period of considerable disruption to sleep patterns. Adolescence is marked by biological changes, such as shifts in circadian rhythms, that delay sleep timing, alongside behavioural factors like increased device use before bed that further disrupts sleep. Together, these changes often lead to chronic sleep restriction (Gradisar et al., 2011). We therefore hypothesised that the transition from pre-adolescence to adolescence would lead to poorer sleep and worse encoding and consolidation of new words. To test this, the AdSleep project has an accelerated longitudinal design to track sleep and word learning across three years in two adolescent cohorts: younger adolescents aged 11-12 and older adolescents aged 13-14. Here, we report findings from the first year of data collection (N = 490). Participants completed a word learning task across two sessions spaced 24 hours apart, designed to assess both initial encoding and overnight consolidation. During session 1, participants learned the word forms, meanings, and sentence contexts of 16 rare English words via transcription, memorisation and production. Memory was tested immediately for half of the words and 24 hours later for the remaining words using cued recall tasks. Sleep was assessed via self-report questionnaires as well as a 2-week sleep diary prior to testing. Objective measures of sleep were derived from actigraphy in a subsample of participants. Bayesian mixed effects models confirmed a substantial difference in sleep patterns between the two age groups. Older adolescents exhibited a stronger evening chronotype and fell asleep 41 minutes later on average than younger children, leading to insufficient sleep relative to age-based recommendations (mean = 7 hrs, 28 mins). They also reported poorer sleep hygiene, notably more frequent afternoon/evening napping, and more frequent device use close to bedtime. In the word leaning task, older adolescents outperformed younger adolescents at encoding, but underperformed at delayed recall, suggesting age-related improvements in encoding capacity were offset by weaker overnight consolidation. Sleep hygiene significantly predicted both encoding and consolidation performance across all tasks (βs = 0.10 - 0.56), with better sleep hygiene associated with improved performance. These findings suggest that poor behavioural choices around bedtime may contribute to the trade-off between improved encoding capacity and reduced consolidation efficiency in the transition from pre-adolescence to adolescence. This supports theories of word learning that assign a key role for sleep and suggest that interventions targeting modifiable sleep behaviours could benefit word learning in adolescence.
Topic Areas: Language Development/Acquisition,