To achieve optimal athletic performance and competition readiness, it is crucial to balance the highest appropriate training stimulus with sufficient recovery. Excessive and/or progressive increases in training load are integral to improving athletic performance (Halson, 2014). However,
increased training loads and/or inadequate recovery can result in maladaptation to training, and if continued, can lead to the development of overreaching/overtraining (Meeusen et al., 2013; Cadegiani and Kater, 2017). In terms of recovery, sleep is an essential component of an athlete’s recuperation due to its physiological and psychological restorative effects (Dinges et al., 1997; Pejovic et al., 2013). Sleep quantity and quality declines following augmented increases (+30%) in training load (Hausswirth et al., 2014), and poor sleep is a common complaint among overreached and/or overtrained athletes (Wall et al., 2003). Regardless of whether reduced sleep is a cause or effect of overreaching and/or overtraining, it is possible that measures of sleep could serve as an indicator of the presence of overreaching and/or overtraining. This opinion article will examine the current research underpinning the relationship between insufficient sleep and the development of overreaching/overtraining, describe the implications for practitioners (e.g., sport and exercise scientists, coaches), and identify areas for future research.