CRH and myalgic encephalomeyelitis/chronic fatigue syndrome: HPA axis hypoactivity is a characteristic feature in some people with ME/CFS [157,158], for example, low baseline levels of HPA axis hormones, aberrant diurnal hormone levels, reduced HPA axis responses to provocation by corticotropin-releasing hormone (CRH) or adrenocorticotropic hormone (ACTH), blunted HPA axis responses to physical and psychological stress, and enhanced sensitivity to glucocorticoids [159-165].