Children with PTSD have a normal circadian rhythm of cortisol, but pre-bedtime levels remain higher than in healthy controls.

“the normal circadian rhythmicity of cortisol was there it was higher uh early in the morning which we need to jump out of bed and as the day progresses it decreases uh very helpful it goes up when we are stressed like when we have lunch after we have lunch cortisol goes up right so that we can help manage the insult of digestion or or whatever uh and this kids were having those levels but something was happening uh in a number of studies and we noted that the pre-bedtime level was higher”