The effect of intermittent fasting during Ramadan on sleep, sleepiness, cognitive function, and circadian rhythm
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Studies have shown that experimental fasting can affect cognitive function, sleep, and wakefulness patterns. However, the effects of experimental fasting cannot be generalized to fasting during Ramadan due to its unique characteristics. Therefore, there has been increased interest in studying the effects of fasting during Ramadan on sleep patterns, daytime sleepiness, cognitive function, sleep architecture, and circadian rhythm.
In this review, we critically discuss the current research findings in those areas during the month of Ramadan.
Available data that controlled for sleep/wake schedule, sleep duration, light exposure, and energy expenditure do not support the notion that Ramadan intermittent fasting increases daytime sleepiness and alters cognitive function. Additionally, recent well-designed studies showed no effect of fasting on circadian rhythms. However, in non-constrained environments that do not control for lifestyle changes, studies have demonstrated sudden and significant delays in bedtime and wake time.
Studies that controlled for environmental factors and sleep/wake schedule reported no significant disturbances in sleep architecture. Nevertheless, several studies have consistently reported that the main change in sleep architecture during fasting is a reduction in the proportion of REM sleep.
KeywordsChronotype Sleep architecture Alertness Food Light Caloric intake Cognitive function
This study was supported by a grant from the National Plan for Science and Technology Program by the King Saud University Project in Saudi Arabia. The sponsor had no role in the design or conduct of this research.
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Conflict of interest
All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.
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