Effects of acute sleep deprivation and extreme fatigue on cognitive performance and cardiac autonomic function during an expedition adventure race: a case report.

Four ultra-endurance athletes (3M/1F) navigated ~800 km via trekking, biking, and paddling using topographical maps and compass, sleeping ~6 h each. Mood, cognitive performance, and heart rate variability were measured at baseline (PRE), post-race (POST), and 18-h post-race (POST18). Decreased anxiety (ΔMdn = 6.5, p = 0.047) along with increased fatigue (ΔMdn = 13.5, p = 0.02) and confusion (ΔMdn = 5.5, p = 0.02) at POST, and improved reaction time (ΔMdn = 0.12 ms, p = 0.04) at POST18 were observed. Findings suggest that extreme exertion and acute sleep-deprivation can elevate psychological stress; however, improvements 18-h post-race indicates recovery. Findings may have applications for professionals operating under extreme stress, e.g., military, healthcare professionals, disaster response, and elite sport.