Associations Among Sleep and Cancer Risk Behaviors: a Scoping Review of Experimental Studies in Healthy Adult Populations.

backgroundLinks among poor sleep and cancer risk behaviors have been largely overlooked in the context of cancer prevention and behavioral medicine. The goal of this scoping review was to determine the extent and nature of experimental studies conducted with healthy adult populations that tested the associations among poor sleep and cancer risk behaviors.

methodElectronic databases and major sleep journals were searched to identify experimental studies in healthy adult samples published through January 2018. Studies examined associations among eight pairings of manipulated behaviors and outcomes ("independent variable (IV)-outcome pairs"): the impact of sleep manipulations on physical activity (PA), diet, alcohol consumption, and tobacco use outcomes; and the impact of PA, diet, alcohol consumption, and tobacco use manipulations on sleep outcomes. Studies were characterized in terms of sample characteristics; study design; IV type, dose, and duration; and outcome measurement and duration.

resultsAbstracts of 5697 papers and 345 full texts were screened. Eighty-eight studies describing 125 comparisons met inclusion criteria. Only two studies tested the association between tobacco use and sleep; none tested whether sleep influenced alcohol consumption. Sample sizes were typically small, most studies used crossover designs, and studies tended to include younger and more male participants. Within each IV-outcome pair, there was substantial heterogeneity in how behaviors were manipulated, outcome measurement, and type of control group. Few studies assessed mechanisms.

conclusionThere is a need for larger experimental studies with more representative samples. Overall, heterogeneity and limitations in study designs make it difficult to synthesize evidence across studies.