Sleep extension in athletes: what we know so far - A systematic review.

<bold>Objective: </bold>This study reviewed systematically the effects of sleep extension on sports performance.<bold>Design: </bold>Systematic review.<bold>Method: </bold>The systematic review was conducted in November 2020. Articles published in English were searched in PubMed, Virtual Health Library, SPORTDiscus, and Web of Science and Scopus databases. The search terms used were "sleep extension" AND athlete. The measures of interest were sports performance. Studies were included if they were a) original articles, b) published in English and peer-reviewed article, c) had only athletes as participants, d) experimental protocol whose objective was to investigate the effects of sleep extension on sports performance, including randomized (RCT) and non-randomized controlled trial (nRCT), and e) at least a sports performance measure as a dependent variable.<bold>Results: </bold>The primary search revealed that a total of 5 out of 74 articles were considered eligible and 2 studies were subsequently included. The studies used different strategies to extend time in bed or total sleep time (extending 26-106 min). From fifteen sports measures, six presented a large effect size, and the others ranged from trivial to medium. Overall, the risk of bias was high to RCT and low to nRCT and the quality of evidence ranged from very low quality to moderate quality in ten outcomes.<bold>Conclusions: </bold>The limited evidence suggests that sleep extension interventions may be beneficial to improve sports performance in athletes where the magnitude is dependent on the variable assessed, although such conclusions are tentative because of the quality of the evidence and risk of bias. [ABSTRACT FROM AUTHOR]