Circadian Rhythms in Major Depressive Disorder: Mechanistic Insights and Therapeutic Frontiers

This review examines how disruption of circadian rhythms contributes to major depressive disorder through dysregulation of sleep-wake cycles, mood patterns, and genetic variants in clock genes (CLOCK, TIMELESS, CRY1), along with abnormal HPA axis and melatonin signaling. Emerging evidence supports chronotherapeutic approaches such as light therapy and targeted sleep interventions as evidence-based treatments that could be personalized using genetic and molecular markers.