Yeah we are supposed to be waking up , having a boost of cortisol and tapering down at night. But that extra evening boost has us up tesearching, learning and for sure not sleeping. Here's an article that says how it should be.
http://adrenalfatiguesolution.com/cortisol-levels-change-throughout-day/
Cortisol levels are generally high in the morning as we wake from a prolonged period of sleep, with an increase of up to fifty percent in the twenty to thirty minutes after waking. This is known as the ‘cortisol awakening response’. Then, as the day progresses, our cortisol levels naturally begin to drop in a fairly constant and regular fashion that is termed a diurnal rhythm, ending up as low in the late evening. This allows the body to keep a regular sleeping pattern, with the cortisol level dropping for periods of sleep, then replenishing during the following morning
Issie.