Abstract
Twenty healthy young males were studied in Libya over a period one week before Ramadan to one week after it. Control values were obtained from the weeks before and after Ramadan, and experimental values from the first and last weeks of Ramadan. Participants answered a questionnaire about their sleep and naps, the food and fluid ingested, and activities they had undertaken. They also gave a urine sample for measurement of osmolality, measured grip strength and performed a 15-min bout of exercise. The rise in heart rate and perceived exertion during exercise and blood lactate after exercise were measured. Nocturnal sleep and daytime dehydration, activities and sleepiness, perceived exertion when exercise was undertaken, lactate metabolism and responses to physical activity all changed during Ramadan. In addition, there were compensatory changes after sunset. These results contribute to an understanding of physiological changes during Ramadan in healthy individuals. Keywords: drinking; eating; sleepiness; physical performance; mental performance; social activity