Study links depression to biological clock issues

A new study suggests that about one in four cases of depression may be connected to disruptions in the body's biological clock, according to researchers from the University of Sydney. The findings, published in the British Journal of Psychiatry, suggest that this type of depression, called "circadian depression," may not respond well to traditional antidepressants but could be helped by melatonin or specific habits like getting sunlight early in the morning.

Circadian depression identified in 23% of participants

The study involved more than 10,000 Australians with severe depression who completed questionnaires about their sleep habits and how their symptoms changed with the seasons. Participants also gave saliva samples for DNA analysis. Among them, 23% were identified as having circadian depression, which is marked by at least three of six signs of biological clock disruption, such as being a night owl, sleeping more when depressed, and experiencing major mood and energy changes with the seasons.

Biological clock influences mood and behavior

Ian Hickie, a co-author of the study and professor at the University of Sydney, explained that the biological clock affects mood, metabolism, concentration, and the sleep-wake cycle. When this clock is disrupted, people may feel tired, gain weight, have poor sleep, or experience changes in behavior. Hickie noted that modern lifestyles, which often involve staying indoors, using computers, avoiding light, and staying up late, are not in line with the body's natural rhythms.

Genetics may play a role in circadian depression

The study also suggests that genetic factors may contribute to disruptions in the biological clock and the resulting mood disorders. Researchers are planning a clinical trial to see if melatonin, a hormone that helps regulate the sleep-wake cycle, could effectively treat depression linked to circadian rhythm. However, more research is needed before this type of depression can be officially recognized as a new subtype.

Study advances understanding of depression's causes

Colleen Loo, an Australian psychiatrist and professor at the University of New South Wales in Sydney, said the study's findings are helpful for understanding the role of circadian rhythms in depression and how it might be connected to biological factors like genetics and inflammation markers.