We have divided the disorders of homeostasis that occur in patients with BD and its recognized risk factors into: (a) cytokine and inflammatory disorders, (b) use of corticosteroids, (c) HPA axis disorders, (d) sleep disorders, (e) BDNF deficiency, (f) hyperactivity of the kynurenine pathway, (g) structural changes in the CNS, (h) neurotransmission disorders, (i) oxidative stress. This evidence concerns the gene BDNF and sleep disorder.