Ramadan's Hidden Challenge: Sleep Deprivation Outweighs Hunger in Athletes Brief Running Title: Sleep Loss Outweighs Fasting in Athletes During Ramadan

Abstract

Ramadan fasting introduces significant disruptions to sleep and nutrition, posing potential challenges for athletes who must maintain both cognitive and physical performance. While fasting alone has been suggested to have minimal cognitive impact, sleep deprivation during Ramadan remains an understudied factor in athletic performance. This study aimed to investigate the independent and combined effects of sleep restriction and fasting on cognitive performance in elite athletes. A within-subject, repeated-measures design was employed, with 41 elite athletes completing three conditions: (1) Well-Rested Fed (WR-Fed), (2) Well-Rested Fasted (WR-Fast), and (3) Sleep-Restricted Fasting (SR-Fast). The WR-Fed condition was assessed before Ramadan under habitual sleep and eating patterns, while the Ramadan conditions (WR-Fast and SR-Fast) were conducted during the first week of fasting. Sleep duration was objectively tracked using Apple Watches, and cognitive performance was assessed using the Psychomotor Vigilance Test (PVT), Upper-Body Reaction Time, and Go/No-Go Test. A repeated-measures ANOVA was used to analyze cognitive performance across conditions. Athletes in the SR-Fast condition exhibited significantly slower reaction times, greater reaction time variability, and an increased number of lapses compared to both WR-Fed and WR-Fast conditions (p < .05). WR-Fast led to mild impairments in reaction time variability and lapses, the magnitude of these effects was considerably smaller than those induced by sleep restriction. These findings provide novel insights into the neurocognitive effects of Ramadan and underscore the need for tailored interventions to support athletic performance under combined sleep and nutritional stress.