P023 Defining sleep hygiene in the scientific literature: A bibliographic review of observational studies

INTRODUCTION: ‘Sleep hygiene’ is a term used to describe the behavioural and environmental factors within an individual’s control that can influence sleep outcomes. There is no universal consensus on this definition and what factors comprise sleep hygiene. The aim of this systematic scoping review is to define sleep hygiene based on its use in published observational studies. METHODS: A search of MEDLINE, EMBASE, PsycINFO and CINAHL databases was conducted from inception until 31st December 2021 using the phrase ‘sleep hygiene’ in the title or abstract. RESULTS: The search identified 250 eligible studies. Studies’ definitions of sleep hygiene converged on three themes: behavioural factors, environmental factors, and an aspect of control. Factors included in individual studies included caffeine (included in 68% of studies), sleep timing (67%) alcohol (65%), exercise (64%), light (62%), smoking (62%) a comfortable environment (60%), wind-down routine (60%), napping (58%), noise (54%), stress (53%), other psychological factors (49%), stimulus control (49%), bed restriction (41%), food intake (28%), other substances (20%) and sleep medications (16%). The most common method of measuring sleep hygiene was the Sleep Hygiene Index, used by 71 studies (28%). DISCUSSION: This review showed researchers’ understanding of sleep hygiene to include modifiable behavioural and environmental factors that influence sleep, however, the elements included were highly variable, as were the details of each element. The inconsistency in researchers’ understanding of sleep hygiene implies inconsistency in research results. This may act as a barrier to providing the best evidence-based sleep health education and sleep health promotion.