The Influence of Circadian Rhythm on Depression

Depression is a common mental disorder with key symptoms such as low mood, anhedonia, cognitive impairment, and sleep disturbances. The rising prevalence of depression underscores the need to investigate its relationship with circadian rhythm, which could enhance current treatment approaches, such as light therapy and melatonin supplementation. Many individuals with depression experience insomnia, delayed sleep phase, and fragmented sleep, which is related to circadian dysfunction. Circadian rhythm is typically controlled by the suprachiasmatic nucleus and other external clues, such as light or meal timing. An impact on genetic bases or external factors could disrupt circadian rhythm. Epidemiological, clinical, and animal studies have revealed the bidirectional relationship between circadian disruption and depression with supporting evidence. This essay focuses on the bidirectional relationship between depression and circadian rhythm. Furthermore, this essay will discuss how clock genes, neurotransmitters, the HPA axis, oxidative stress, and mitochondrial dysfunction induce depression and circadian disruption.