0548 Overnight Memory Consolidation in Insomnia versus Normal and Experimentally Disrupted Sleep

Abstract

Abstract Introduction Healthy sleep is assumed to play an important role in the consolidation of newly acquired memories. Evidence suggest that periods of sleep after learning facilitates memory consolidation relative to wakefulness. Insomnia is associated with cognitive impairment but few studies have assessed overnight memory consolidation. We compared overnight consolidation in people with insomnia to a group of good sleepers who were randomised to either a normal night of sleep (uninterrupted sleep, US) or one night of sleep continuity disruption via forced awakenings (FA). Methods 51 good sleepers (37 female; mean age: 24 years, SD: 3.63), randomised to either one night of US (n=24) or one night of FA (n=27), were compared to 27 participants meeting criteria for insomnia disorder (23 female; mean age: 53 years, SD: 8.34) who were assessed at baseline as part of a randomised controlled trial of digital cognitive-behavioural therapy. Overnight memory consolidation (difference in correctly recalled word pairs between evening and morning recall) was assessed using the same word-pair task and protocol in the two lab-based studies. Results Overnight memory consolidation was significantly lower in the insomnia (mean: 5.4, SD: 5.8, p=0.001) and the FA (mean: 6.7, SD: 4.1, p<0.001) group compared to the US group (mean: 11.6, SD: 5.3). However, when adjusted for age only the FA group, but not the insomnia group, showed significantly lower memory performance than the US group. Conclusion While our findings suggest that overnight memory consolidation is impaired in insomnia relative to normal sleep we cannot rule out an age-related explanation given the difference in ages between the study samples. Future work will assess whether overnight consolidation improves following cognitive behavioural therapy. Support The research was supported by the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC) and the Dr Mortimer and Theresa Sackler Foundation. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.