Australian Researchers Identify Body-Clock Linked Depression Subtype

Australian researchers have identified a form of depression they call "circadian depression" linked to disruption of the body's internal clock.

The study, published in the British Journal of Psychiatry, analysed clinical and genetic data from 11,380 Australians with mostly severe and recurrent depression. The first author was Dr Emiliana Tonini of the University of Sydney's Brain and Mind Centre. The Guardian

Researchers said about 23% of participants met the criteria for the subtype. They defined it as having at least three of six features: a seasonal pattern of illness, delayed sleep timing, sleeping longer when depressed, being a night owl, waking feeling very tired, and social jetlag.

The centre describes the idea as proposing that body-clock dysregulation is more than just a symptom of some depressive disorders. University of Sydney Brain and Mind Centre For people in this group, the study authors suggested circadian-targeted treatments such as melatonin and light therapy may help. Treatments known as SSRIs and SNRIs were found to be less effective and to have more side effects for people with the subtype.

The analysis was limited to people of genetically inferred European ancestry, which may limit how widely the findings apply to other populations.

Earlier activity in the field included a 2024 guest editorial in the same journal titled 'Chronopsychiatry' by D J Smith. The Brain and Mind Centre also hosts further material on the concept titled "Circadian depression, a closer look at body clocks and mental health." The centre previously won a Wellcome Mental Health Award connected to circadian depression research involving Professor Ian Hickie and an international team. University of Sydney