Background and Objectives: The disruption of the circadian rhythm, driven by modern lifestyle factors such as irregular sleep patterns and artificial light exposure, is increasingly recognized as a critical factor in the pathogenesis of mood disorders. This review aims to comprehensively evaluate the biological mechanisms linking circadian misalignment with Major Depressive Disorder (MDD) and Bipolar Disorder (BD) and to assess the clinical efficacy of lifestyle interventions, specifically sleep hygiene and light therapy. Methodology: A comprehensive literature search was conducted utilizing databases including PubMed and Google Scholar, focusing on peer-reviewed articles, meta-analyses, and systematic reviews published between 2006 and 2025. Results: The synthesized data reveal that circadian disruption significantly exacerbates neuroinflammation and alters melatonin and cortisol secretion, directly correlating with depressive and manic episodes. Furthermore, clinical evidence strongly supports chronotherapeutic interventions; bright light therapy (BLT) and targeted sleep hygiene protocols demonstrate substantial efficacy in mood stabilization and symptom reduction. Conclusion: Circadian realignment should be integrated as a foundational, rather than merely adjunctive, component in the psychiatric management of mood disorders. Future research should prioritize large-scale, controlled trials to optimize chronotherapeutic protocols for individualized patient care.
Noweta et al. (Mon,) studied this question.