The relationship between sleep duration and working memory in children Rebecca Ashton D.Ed.Psy thesis Volume 1, 2016 University College London 1 Contents Abstract .................................................................................................................................................. 6 Background ....................................................................................................................................... 6 Aims .................................................................................................................................................... 6 Sample ............................................................................................................................................... 6 Methods ............................................................................................................................................. 6 Results ............................................................................................................................................... 7 Conclusions ....................................................................................................................................... 7 Literature review ................................................................................................................................... 8 Introduction ........................................................................................................................................ 9 What is sleep? ................................................................................................................................ 10 Development of sleep .................................................................................................................... 11 Cultural influences on sleep .......................................................................................................... 13 Functions of sleep .......................................................................................................................... 16 Working memory ............................................................................................................................ 17 Development of working memory and its neural substrates .................................................... 20 Ways to improve working memory ............................................................................................... 22 Neural mechanisms by which sleep may affect working memory ........................................... 22 Sleep and working memory in children: a systematic literature review .................................. 25 Overview of associations............................................................................................................... 31 No relationship between sleep and working memory? ......................................................... 33 A positive linear relationship between sleep and working memory? .................................. 35 A negative linear relationship between sleep and working memory? ................................. 37 An inverted U relationship between sleep and working memory? ...................................... 39 Weight of evidence assessment .................................................................................................. 41 Conclusions ..................................................................................................................................... 44 Future research .............................................................................................................................. 46 Empirical study ................................................................................................................................... 48 Introduction ...................................................................................................................................... 49 Method ............................................................................................................................................. 55 Study design ............................................................................................................................... 55 Measures ..................................................................................................................................... 57 Intervention .................................................................................................................................. 61 Participants .................................................................................................................................. 63 Results ............................................................................................................................................. 72 Statistical analysis ...................................................................................................................... 72 Baseline measures ..................................................................................................................... 73 Measurement issues .................................................................................................................. 80 Intervention effects ..................................................................................................................... 84 Programme acceptability ........................................................................................................... 94 2 Discussion ...................................................................................................................................... 98 Key findings ................................................................................................................................ 98 Key methodological issues ..................................................................................................... 101 Key theoretical issues ............................................................................................................. 105 Future research ........................................................................................................................ 107 Critical appraisal .............................................................................................................................. 110 The process of research development ..................................................................................... 111 Research questions, methodology and epistemology ........................................................... 113 Intervention-led research ............................................................................................................ 117 Risky research ............................................................................................................................. 119 Using advice from supervisors .................................................................................................. 122 Literature review ...................................................................................................................... 122 Dependence on others ........................................................................................................... 124 Data input and analysis .......................................................................................................... 125 The (un)importance of sleep? .................................................................................................... 126 A distinct contribution .................................................................................................................. 128 Methodology ............................................................................................................................. 128 The relationship between sleep and working memory in children.................................... 129 The future for sleep interventions .......................................................................................... 130 The future for sleep research ................................................................................................. 133 Key messages for educational psychologists ..................................................................... 135 Appendix 1: Ethics approval ......................................................................................................... 163 Appendix 2: Project date planner .................................................................................................. 165 Appendix 3: Sleep diary blank form .............................................................................................. 166 Appendix 4: Actiwatch wearer’s guide .......................................................................................... 167 Appendix 5: Sleep knowledge questionnaire .............................................................................. 169 Appendix 6: Amendments to ACES materials............................................................................. 170 Appendix 7: Flyer to schools ......................................................................................................... 175 Appendix 8: Teacher information & consent form ...................................................................... 176 Appendix 9: Parent and child information & consent form ........................................................ 180 Appendix 10: Scattergrams showing relationships