Li, C. and Li, X. 2026. Mechanisms of Bifidobacterium as an Adjuvant Therapy for Improving Sleep Quality and Neuroendocrine Regulation in Bipolar Disorder: A Narrative Review. Actas Españolas de Psiquiatría. (Oct. 2026), 1–8. DOI:https://doi.org/10.62641/aep.2237.