In addition, acupuncture at SP6-HT7 can downregulate serum adrenocorticotropic hormone (ACTH) and cortisol levels in patients with insomnia, inhibit the hyperactive hypothalamic–pituitary–adrenal axis, increase serum melatonin levels, and improve the function of the SCN-PG-MT system, thus regulating sleep (58, 75). Here, MCAT is linked to insomnia.