Impact of Sleep Deprivation on Oxidative Stress in Amateur Marathon Runners

Thesis Abstract

Sleep deprivation is a pervasive stressor among amateur endurance athletes, with potential to disrupt homeostasis and elevate oxidative stress, thereby compromising performance and recovery. This study addresses the gap in field-based evidence on how acute and chronic sleep restriction affects redox balance in amateur marathon runners, and whether circadian misalignment mediates these effects. The aim is to quantify the relationship between sleep parameters and oxidative stress markers, and to evaluate the downstream impact on endurance performance and perceived exertion. Specific objectives are (1) to determine associations between objectively measured sleep duration and sleep efficiency and biomarkers of oxidative stress and antioxidant capacity; (2) to examine differential effects of weekday versus weekend sleep patterns on oxidative stress; (3) to assess whether sleep-related changes in oxidative stress predict variations in cycling or running performance at maximum and submaximal intensities; (4) to explore moderating roles of training load, hydration, and nutritional intake; and (5) to compare responses across different age groups within the amateur cohort. A prospective, observational cohort design will be employed, with 120 amateur marathon runners aged 20–45 years recruited from regional running clubs. Participants will be assessed over a 12-week training block that includes three long runs and two quality sessions per week. Sleep will be tracked with wrist actigraphy (worn continuously) and self-reported sleep diaries, supplemented by one-week polysomnography (PSG) in a subsample of 20 participants to validate actigraphy data. Oxidative stress will be quantified via plasma malondialdehyde (MDA), F2-isoprostanes, protein carbonyls, and total antioxidant capacity (TAC) measured at baseline, mid-study, and post-block, alongside salivary cortisol as a surrogate marker of physiological stress. Training load will be monitored using session-RPE and GPS-derived external load metrics. Endurance performance will be evaluated through a standardized treadmill time-to-exhaustion test and a 10-km time trial conducted at baseline and after 12 weeks, with rating of perceived exertion (RPE) recorded post-test. Dietary logs and hydration markers will be used to adjust for confounding nutritional influences. Data will be analyzed using mixed-effects linear models to account for repeated measures and individual variance, with sleep duration, sleep efficiency, and circadian misalignment as primary predictors. Regression analyses will examine associations between sleep variables and oxidative stress biomarkers, controlling for age, sex, training load, and diet. Repeated-measures ANOVA will evaluate changes in performance outcomes across time and sleep condition strata. Mediation analyses will test whether oxidative stress mediates the relationship between sleep deprivation and performance decrements. Subgroup analyses will compare those with consistent sleep schedules to those with irregular sleep patterns. The study will be grounded in the Theory of Acute Stress and Resource Depletion and the Allostatic Load framework, providing a mechanistic basis for how sleep disruption translates into oxidative imbalance and performance fatigue. Expected findings include (i) shorter sleep duration and lower sleep efficiency will be significantly associated with elevated MDA, F2-isoprostanes, and protein carbonyls and reduced TAC; (ii) irregular sleep patterns will amplify oxidative responses independent of total weekly training load; (iii) oxidative stress markers will partially mediate the adverse effects of sleep deprivation on endurance performance and RPE; and (iv) PSG-confirmed sleep fragmentation will show stronger associations with oxidative stress than actigraphy-derived measures alone. The study contributes to knowledge by informing evidence-based sleep hygiene guidelines for amateur endurance athletes, integrating objective sleep metrics with biochemical redox profiles, and elucidating the physiological pathways linking sleep and performance. The main conclusion is that sleep deprivation elevates oxidative stress in amateur marathon runners, with significant implications for performance and recovery; robust sleep optimization emerges as a practical intervention to mitigate redox imbalance. Recommendations include implementing individualized sleep strategies, prioritizing consistent bedtimes, strategic napping around key sessions, and monitoring sleep as part of training programming. Further research should extend to interventional trials testing sleep extension and circadian alignment protocols, and to exploring long-term health outcomes associated with repetitive sleep disruption in endurance athletes.