Cross-sectional studies in CFS tend to show basal hypocortisolaemia [22, 23], attenuated diurnal variation [4, 24], an attenuated response to activation by CRH or ACTH [16, 23, 25–28], an enhanced suppression by dex [10, 17, 28–30], and an enhanced dex-induced suppression of IL-6, TNFα, IL-10, and IL-4 synthesis [21, 31, 32] and of peripheral blood mononuclear cell proliferation [18]. This evidence concerns the gene CRH and myalgic encephalomeyelitis/chronic fatigue syndrome.