Author(s): SWIATEK, M., KOMAREK, Z., WIECEK, M., FILIP-STACHNIK, A., Institution: UNIVERSITY SCHOOL OF PHYSICAL CULTURE IN KRAKOW, Country: POLAND, Abstract-ID: 2390

INTRODUCTION:
Sleep and oxygen availability are fundamental for maintaining metabolic homeostasis and central nervous system integrity. High-altitude expeditions frequently involve a dangerous combination of systemic hypoxia and severe sleep restriction (SR). While isolated effects are well-documented, integrative research—particularly protocols reflecting the long-duration physical effort and cumulative fatigue occurring during mountain expeditions—is significantly lacking. This review synthesizes current evidence to identify cognitive risks and gaps in expedition safety.
METHODS:
Reporting followed PRISMA guidelines to ensure methodological transparency and rigor. Studies were identified through PubMed, SPORTDiscus, and Web of Science. Scientific databases were queried using specific search keys: “sleep” OR “sleep deprivation” OR “sleep restriction” AND “mountain” OR “hypoxia” OR “altitude” OR “physical performance” “cognitive performance”. Included were peer-reviewed English articles analyzing sleep manipulation in mountain or hypoxic environments on cognitive or physical performance. Methodological quality was appraised using the Mixed Methods Appraisal Tool (MMAT). Evidence was qualitatively synthesized from five sources, comprising four randomized crossover experimental trials and one large-scale descriptive field study.
RESULTS:
The available literature indicates that while moderate hypoxia alone has limited cognitive effects, its combination with SR significantly degrades performance. Sleep loss—from partial to total deprivation—reduces executive function throughput across domains such as inhibition and working memory. When hypoxia and SR co-occur, individuals report peak levels of subjective mental workload and exhibit increased error rates in complex tracking tasks. Neurophysiologically, SR is the primary driver of diminished attentional capacity and disrupted neural synchronization, with moderate hypoxia exacerbating these existing deficits. The visual attentional system demonstrates higher sensitivity and delayed latencies compared to the auditory system under dual stress. Field data from 1,154 mountain reveals that 80% experience symptoms such as hallucinations (34%) and falls (15%). Crucially, "banking sleep" and 20-minute bouts of moderate exercise can reduce these cognitive decrements
CONCLUSION:
Hypoxia and sleep loss synergistically compromise the prefrontal cortex, the primary region associated with executive functions. While respiratory and ocular parameters provide robust non-invasive monitoring for mental overload, laboratory models currently fail to simulate the cumulative physical fatigue of actual mountain travel. Practically, "sleep banking" reduces fall risks, while prioritizing auditory over visual alerts ensures safety information is processed more effectively under combined stress. Future research must prioritize protocols reflecting the prolonged physical effort occurring during mountain expeditions to accurately model and mitigate expedition risks.