Shorter cites hypothalamic -- pituitary -- adrenal axis ( HPA ) dysregulation and shortened rapid eye movement sleep latency in those with melancholic depression as examples of this evidence .
Pituitary -- adrenal axis ( HPA ) dysregulation is a positive dexamethasone suppression test result .
Shorter cites hypothalamic -- pituitary -- adrenal axis ( HPA ) dysregulation , a positive dexamethasone suppression test result , and shortened rapid eye movement sleep latency in those with melancholic depression as examples of this evidence .