Sleep as a Modifiable Determinant of Cognitive and Physical Performance in Athletes: A Narrative Review of the Last Decade of Research

Background. Sleep is increasingly recognized as an active physiological process essential for nervous system and skeletal muscle function, not a passive state. Sleep quantity and quality are linked to cognitive and physical performance, with clinical relevance for professions requiring sustained vigilance and decision-making under time pressure. Aim. To systematize current knowledge on the impact of sleep quantity and quality on cognitive functioning and physical performance, based on studies from the last decade. Material and methods. This narrative review (not PRISMA-systematic) synthesizes meta-analyses, systematic reviews, and selected primary studies published mainly 2015–2026, with earlier foundational works (1982–2014) still influential in sleep physiology, neuropsychology of sleep deprivation, and exercise physiology, identified through PubMed, Scopus, and Web of Science. Results. Sleep deprivation and restriction were consistently associated with impaired memory consolidation, attention, executive functioning, and emotion regulation, as well as reduced aerobic and anaerobic capacity, muscle strength, neuromuscular coordination, and recovery, alongside increased injury risk. Sleep extension produced measurable, albeit variable, improvements in athletic performance. These effects appear underpinned by shared neurobiological mechanisms — glymphatic function, synaptic homeostasis, hormonal/inflammatory regulation, and amygdala–prefrontal coupling — further modulated by circadian rhythm. Conclusions. Sleep deprivation impairs cognitive and physical performance via shared, overlapping neurobiological pathways, while sleep extension offers a modest but consistent benefit, supporting its use as a practical, low-cost intervention warranting the same systematic attention as training load and nutrition. Given methodological limitations in the evidence base, findings should be applied with caution in athletic, medical, and educational settings.