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PLoS One. 2013 Apr 18;8(4):e60917. doi: 10.1371/journal.pone.0060917. Print 2013.

Relative metabolic stability, but disrupted circadian cortisol secretion during the fasting month of Ramadan.

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Department of ClinicalBiochemistry-Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia.



Chronic feeding and sleep schedule disturbances are stressors that exert damaging effects on the organism. Practicing Muslims in Saudi Arabia go through strict Ramadan fasting from dawn till sunset for one month yearly. Modern era Ramadan practices in Saudi Arabia are associated with disturbed feeding and sleep patterns, namely abstaining from food and water and increasing daytime sleep, and staying awake and receiving food and water till dawn.


Strict Ramadan practices in Saudi Arabia may influence metabolism, sleep and circadian cortisol secretion.


Young, male Ramadan practitioners were evaluated before and two weeks into the Ramadan. Blood samples were collected at 9.00 am and 9.00 pm for measurements of metabolic parameters and cortisol. Saliva was collected serially during the day for cortisol determinations.


Ramadan practitioners had relative metabolic stability or changes expected by the pattern of feeding. However, the cortisol circadian rhythm was abolished and circulating insulin levels and HOMA index were increased during this period.


The flattening of the cortisol rhythm is typical of conditions associated with chronic stress or endogenous hypercortisolism and associated with insulin resistance.


Modern Ramadan practices in Saudi Arabia are associated with evening hypercortisolism and increased insulin resistance. These changes might contribute to the high prevalence of chronic stress-related conditions, such as central obesity, hypertension, metabolic syndrome and diabetes mellitus type 2, and their cardiovascular sequelae observed in the Kingdom.

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