Effects of Length of Time of Fasting upon Subjective and Objective Variables When Controlling Sleep, Food and Fluid Intakes

Authors: H. Alabed, K. Abuzayan. L. Fgie, K. Zarug

Abstract:

Ramadan requires individuals to abstain from food and fluid intake between sunrise and sunset; physiological considerations predict that poorer mood, physical performance and mental performance will result. In addition, any difficulties will be worsened because preparations for fasting and recovery from it often mean that nocturnal sleep is decreased in length, and this independently affects mood and performance.

A difficulty of interpretation in many studies is that the observed changes could be due to fasting but also to the decreased length of sleep and altered food and fluid intakes before and after the daytime fasting. These factors were separated in this study, which took place over three separate days and compared the effects of different durations of fasting (4, 8 or 16h) upon a wide variety of measures (including subjective and objective assessments of performance, body composition, dehydration and responses to a short bout of exercise) - but with an unchanged amount of nocturnal sleep, controlled supper the previous evening, controlled intakes at breakfast and daytime naps not being allowed. Many of the negative effects of fasting observed in previous studies were present in this experiment also. These findings indicate that fasting was responsible for many of the changes previously observed, though some effect of sleep loss, particularly if occurring on successive days (as would occur in Ramadan) cannot be excluded.

Keywords: Drinking, Eating, Mental Performance, Physical Performance, Social Activity, Blood, Sleepiness.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1093500

References:

[1] S.Carvalho-Bos, J. Waterhouse, B. Edwards, R. Simons, and T. Reilly. The use of actimetry to assess changes to the rest-activity cycle. Chronobiology International, 20:2003, 1039-1059.
[2] B. J. Edwards, and J. Waterhouse, (Effects of one night of partial sleep deprivation upon diurnal rhythm of accuracy and consistency in throwing darts). Chronobiology International, 26: 2009, pp. 1–15.
[3] B. Edwards, B. Waterhouse, G. Atkinson, and T. Reilly, (Effects of time of day and distance upon accuracy and consistency of throwing darts). Journal of Sports Sciences. 25: 2007, pp. 1531-8.
[4] T. Reilly, and J. Waterhouse, (Altered sleep-wake cycles and food intake): the Ramadan model. Physiology and Behavior, 90: 2007, pp. 219–228.
[5] T. Reilly, G. Atkinson, and J. Waterhouse, (Biological Rhythms and Exercise). Oxford: Oxford University Press. 1997.
[6] P. Valdez, T.Reilly, and J. Waterhouse, J.(Rhythm of mental performance). Mind, Brain, and Education, 2: 2010, 7-16.
[7] J. Waterhouse, (Effects of Effects of Ramadan on physical performance): Chronobiological considerations; British Journal of Sports Medicine, (In press).2010.
[8] J. Waterhouse, T. Akerstedt, M. Lennernas, and J.Arendt, (Chronobiology and nutrition: internal and external factors. Canadian of Journal Diabetes Care,23, 1999, pp. 82–88.
[9] J. Waterhouse, H. Alabed, B. Edwards, and T. Reilly, (Changes in sleep, mood and subjective and objective responses to physical performance during the daytime in Ramadan). Biological Rhythm Research. 40: 2009, pp. 1 – 17.
[10] J. Waterhouse, L. Alkib, B. Edwards, and T. Reilly, (Diurnal changes in sleep, food and fluid intakes, and activity during Ramadan), 2006, in the UK some preliminary observations. Biological Rhythm Research, 39: 2008a, pp. 449-469.
[11] J. Waterhouse, L. Alkib, B. Edwards, and T. Reilly, (Effects of Ramadan upon Fluid and Food Intake, Fatigue, and Physical, Mental, and Social Activities) A Comparison between the UK and Libya. Chronobiology International, 25, 2008b, pp. 697-724.
[12] J. Waterhouse, D. Minors, T. Akerstedt, T. Reilly, and G. Atkinson, (Rhythms in human performance). In: Takahashi J, Turek F, Moore R, editors. Circadian clocks. New York: Kluwer Academic/Plenum Publishers, 2001, pp. 571–601.