Purpose <p>This narrative review explores the complex relationship between sleep, athletic performance, and recovery, emphasizing the physiological mechanisms at play.</p> Methods <p>This review included papers reporting physiological mechanisms linking sleep, athletic performance, and recovery. Literature was identified through targeted searches in relevant databases and bibliographies of referenced scientific articles. Retrieved studies were analyzed thematically according to major domains, enabling integration of foundational mechanisms with applied evidence to inform practice and future research.</p> Results <p>Slow-wave sleep (SWS) plays an important role in physical recovery, with its increase during the night being linked to rises in metabolic stress and growth hormone production. When training volume and/or intensity increase, a corresponding increase in SWS is usually observed, but a fine line may exist between promotion and disruption of sleep (i.e., overtraining). Acute sleep deprivation or restriction may influence sports performance differently, depending on the sport. In sports requiring complex skills or high cognitive demands, impairments may be more pronounced. Among the main strategies, napping has received the greatest attention, as it serves as a supplement to nighttime sleep and is associated with improvements in fatigue and sleepiness perception and physical and cognitive performance. Sleep extension has been studied less, but existing evidence shows improvements in cognitive and physical performance, as well as sport-specific skill execution.</p> Conclusions <p>Despite the growing body of research on athletes’ sleep patterns and their impact on performance, there is limited focus on the underlying mechanisms and practical benefits of sleep.</p>