Exercise interventions to improve sleep in cancer patients: A systematic review and meta-analysis

Exercise leads to several positive outcomes in oncology. However, the question as to whether exercise is a valuable option for improving patients' sleep, which is frequently disturbed in cancer patients, remains unanswered. The aims of this study were to conduct a systematic review and meta-analysis of randomized and non-randomized clinical trials that have investigated the effect of exercise on sleep outcomes, assessed subjectively and objectively. Relevant studies, published before May 2016, were traced through a systematic search of PubMed, Embase, PsycINFO, SportDiscus and Cochrane library databases. The review looked at twenty one trials, including 17 randomized controlled trials. Most interventions were home-based aerobic walking programs and breast cancer patients were the subgroup most represented. Sleep variables were most commonly used as secondary outcomes in the reviewed studies. Studies were highly heterogeneous in terms of methodology. The qualitative review of available evidence suggested a beneficial effect of exercise interventions on sleep in several studies (48%). However, the meta-analysis conducted on RCTs revealed no significant effect either on subjective or on objective sleep measures. This lack of significant effect could be due, at least in part, to a floor effect. More rigorous studies are needed to assess the effect of exercise interventions in cancer patients, in particular randomized controlled trials conducted in patients with clinically significant sleep disturbances at baseline.