Intermittent fasting, particularly during the month of Ramadan, presents unique physical and psychological challenges, influencing various aspects of daily functioning, including sleep and cognitive performance. The aim of the present study was to assess the effect of intermittent fasting on sleepiness and sleep quality. In addition, it aims to examine its effects, when associated to mental fatigue on memory, vigilance and readiness for training in athletes. Twenty-five Tunisian kick-boxers completed self-administered questionnaires to evaluate sleepiness, sleep quality and duration, fatigue, vigilance, concentration, and motivation at three points: ten days before Ramadan, mid-Ramadan, and at its end. Overall, the results indicated that athletes reported improvements in somnolence, sleep quality, vigilance, concentration, and motivation by the end of Ramadan, despite stable sleep duration and consistent levels of fatigue across the three periods. Additionally, working memory, visual vigilance and reaction time performance were superior at the end of Ramadan compared to the other periods, regardless of whether the assessment occurred before or after the mental fatigue task. These findings contribute to the understanding of the complex interplay between fasting, sleep, mental fatigue and cognitive performance.
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