Writing in Psychoneuroendocrinology, researchers noted children with the autistic condition do not experience the normal morning "surge" of cortisol.
This may explain their need for routine and aversion to change, they suggested.
"Cortisol is one of a family of stress hormones that acts like a 'red alert' that is triggered by stressful situations allowing a person to react quickly to changes around them," said Mark Brosnan, a psychologist at
"In most people, there is a two-fold increase in levels of this hormone within 30 minutes of waking up, with levels gradually declining during the day as part of the internal body clock."Our study found that the children with AS [Asperger's Syndrome] didn't have this peak, although levels of the hormone still decreased during the day as normal.
"We would now like to see similar work in adults."
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