This is from Precision Nutrition (Dr. John Berardi's site) and not sure the validity or the source of the research but probably enough to test if you have elevated levels of cortisol. He states sources at the end of the article but none that specifically would direct me for more information on the stated findings.
"Time of day and time of eating
The degree of cortisol release during high intensity exercise depends in part on the time of day and the timing of meals. When exercise is performed during a time of already high cortisol levels (for example, in the morning), it doesn’t increase above already elevated levels.
Cortisol secretion displays 7 to 15 spontaneous or meal-associated “pulses” throughout the day.
Cortisol circadian rhythms are closely coupled to the sleep-wake cycle. Peak cortisol release occurs between 7 and 9 in the morning, the time of dark-light transition."
Click here for a link to the article.
