Background: Sedentary behaviour (SB) is a risk factor for chronic disease and premature mortality. While many individual studies have examined the reliability and validity of various self-report measures for assessing SB, it is not clear, in general, how self-reported SB (e.g., questionnaires, logs, ecological momentary assessments (EMAs)) compares to device measures (e.g., accelerometers, inclinometers). Objective: The primary objective of this systematic review was to compare self-report versus device measures of SB in adults. Methods: Six bibliographic databases were searched to identify all studies which included a comparable self-report and device measure of SB in adults. Risk of bias within and across studies was assessed. Results were synthesized using meta-analyses. Results: The review included 185 unique studies. A total of 123 studies comprising 173 comparisons and data from 55,199 participants were used to examine general criterion validity. The average mean difference was -105.19 minutes/day (95% CI: -127.21, -83.17); self-report underestimated sedentary time by~1.74 hours/day compared to device measures. Self-reported time spent sedentary at work was~40 minutes higher than when assessed by devices. Single item measures performed more poorly than multi-item questionnaires, EMAs and logs/diaries. On average, when compared to inclinometers, multi-item questionnaires, EMAs and logs/diaries were not significantly different, but had substantial amount of variability (up to 6 hours/day within individual studies) with approximately half over-reporting and half under-reporting. A total of 54 studies provided an assessment of reliability of a selfreport measure, on average the reliability was good (ICC = 0.66). Conclusions:Evidence from this review suggests that single-item self-report measures generally underestimate sedentary time when compared to device measures. For accuracy, multi-item questionnaires, EMAs and logs/diaries with a shorter recall period should be encouraged above single item questions and longer recall periods if sedentary time is a primary outcome of study. Users should also be aware of the high degree of variability between and within tools. Studies should exert caution when comparing associations between different self-report and device measures with health outcomes. Systematic review registration: PROSPERO CRD42019118755

The purpose of this overview of systematic reviews was to determine the relationship between different types and patterns of sedentary behaviour and selected health outcomes in adults and older adults. Five electronic databases were last searched in May, 2019, with a 10-year search limit. Included reviews met the a priori population (community-dwelling adults aged 18 years and older), intervention/exposure/comparator (various types and/or patterns of sedentary behaviour), and outcomes criteria. Eighteen systematic reviews were included in the evidence synthesis. High levels of sedentary behaviour are unfavourably associated with cognitive function, depression, function and disability, physical activity levels, and physical health-related quality of life in adults. Reducing or breaking up sedentary behaviour may benefit body composition and markers of cardiometabolic risk. Total sedentary behaviour and TV viewing were most consistently associated with unfavourable health outcomes, while computer and Internet use may be favourably associated with cognitive function for older adults. The quality of evidence within individual reviews (as assessed by review authors) varied from low to high, while the certainty of evidence was low to very low. These findings have important public health implications, suggesting that adults should avoid high levels of sedentary behaviour and break-up periods of prolonged sitting. (PROSPERO registration nos.: CRD42019123121 and CRD42019127157.) Novelty High levels of sedentary behaviour are unfavourably associated with important health outcomes in adults. Reducing or breaking up sedentary behaviour may benefit body composition and markers of cardiometabolic risk. Computer and Internet use may be favourably associated with cognitive function in older adults.

Background The purpose of this study was to systematically review the relationship between the timing of sedentary behaviours and access to sedentary activities in the bedroom with sleep duration and quality in children and youth. A secondary purpose was to examine whether these relationships differ when comparing screen-based and non-screen-based sedentary activities. Methods We searched four databases for peer-reviewed studies published between 1 January 2010 and 19 January 2021. Risk of bias assessment for each study and certainty of evidence were assessed using the GRADE framework. Results We identified 44 eligible papers reporting data from 42 separate datasets and including 239 267 participants. Evening participation in screen-based sedentary behaviours and access to screen-based devices in the bedroom were associated with reduced sleep duration and quality. Daytime screen use was also associated with reduced sleep duration, although this was examined in relatively few studies. Whether performed during the day or night, non-screen-based sedentary behaviours were not consistently associated with sleep duration or quality. The quality of evidence was rated as low to very low for all outcomes. Conclusion In order to maximize sleep duration and quality, children and youth should be encouraged to minimize screen time in the evening and remove screens from bedrooms. (PROSPERO registration no.: CRD42020189082)

Introduction L’objectif de cette étude était d’effectuer une revue systématique des relations entre, d’une part, l’horaire des comportements sédentaires et l’accès à des activités sédentaires dans la chambre et, d’autre part, la durée et la qualité du sommeil chez les enfants et les adolescents. Un objectif secondaire consistait à vérifier si ces relations étaient différentes selon le type d’activité sédentaire, c’est-à-dire selon si l’activité était liée à l’utilisation des écrans ou non. Méthodologie Nous avons cherché dans quatre bases de données les études ayant fait l’objet d’une évaluation par les pairs publiées entre le 1er janvier 2010 et le 19 janvier 2021. Le risque de biais pour chaque étude et le degré de certitude des données probantes ont été évalués en recourant à l’approche GRADE (Grading of Recommendations Assessment, Development and Evaluation). Résultats Nous avons trouvé 44 articles correspondant à nos critères de recherche, qui portaient sur des données issues de 42 bases de données et 239 267 participants. L’adoption de comportements sédentaires liés à l’utilisation des écrans le soir et l’accès à des écrans dans la chambre ont été associés à une baisse de la durée et de la qualité du sommeil. L’utilisation des écrans pendant la journée a aussi été associée à une baisse de la durée du sommeil, ce paramètre n’ayant cependant été pris en compte que dans relativement peu d’études. Qu’ils soient diurnes ou nocturnes, les comportements sédentaires non liés à l’utilisation des écrans n’ont pas été associables systématiquement à la durée ou à la qualité du sommeil. La qualité des données probantes a été évaluée comme étant faible à très faible pour tous les résultats. Conclusion Pour que la durée et la qualité du sommeil soient optimales, il faudrait nciter les enfants et les adolescents à réduire au minimum le temps passé devant les écrans le soir et bannir les écrans de leur chambre. (no d'enregistrement dans PROSPERO : CRD42020189082)