Associations between objectively measured sleep and cognition in older Icelandic adolescents

• Main Author: Stefánsdóttir, Rúna Sif
• Other Authors: Erlingur Jóhannsson, Faculty of Health Promotion, Sports and Leisure Studies (UI), Deild heilsueflingar, íþrótta og tómstunda (HÍ), Menntavísindasvið (HÍ), School of education (UI), Háskóli Íslands, University of Iceland
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Iceland, School of Education, Faculty of Health Promotion, Sport and Leisure Studies 2022
• Subjects: Svefn; Unglingar; Actigraph; Námsárangur; Doktorsritgerðir; Reykjavík; Iceland
• Online Access: https://hdl.handle.net/20.500.11815/2992

Abstract Background: Insufficient sleep is associated with an increased risk of a variety of negative health outcomes and has been shown to adversely affect academic and cognitive function. Despite strong evidence of the deleterious effects of short and disrupted sleep on health, studies that use objective methods to measure adolescent free-living sleep, in general, and its association with academic and cognitive performance, specifically, are scarce, particularly during the critical transition from compulsory to secondary education. Aim: The aim of this research was to use objective measures to quantify the free-living sleep of Icelandic adolescents at ages 15 and 17, as they transition from compulsory to secondary education, and to determine whether their sleep patterns are associated with academic and cognitive outcomes. Methods: The study sample came from six elementary schools in Reykjavík, Iceland. One week of free-living sleep measured with wrist actigraphy was collected at two time points. The first wave of data collection occurred in 2015, where 280 participants had valid sleep data (mean age 15.9±0.3 years). Two years later, 199 participants had valid sleep data (mean age of 17.7±0.3 years). In total, 145 participants had complete data at both data collection points. During the first wave of data collection, academic achievement was objectively quantified using the combined score from standardized national examinations administered to all 10th grade students in mathematics, English, and Icelandic. During the second wave of data collection, an n-back working memory task and Posner cue-target visual attention task were used to objectively assess cognitive function. Results: Over all measured nights at both time points, Icelandic adolescents averaged late bedtimes (00:43 at age 15, 01:12 at age 17), short total sleep time (6.6 ± 0.7 h/night at age 15 and 6.2 ± 0.7 h/night at age 17) and high variability in total sleep time (weekly standard deviations of 1.3 h and 1.4 h at ages 15 and 17, respectively). ...