# One in four with severe depression have circadian type > Australian researchers identify a depression subtype linked to body clock disruption, with distinct symptoms and genetic markers. - Title: One in four with severe depression have circadian type · Abc - Summary: Australian researchers identify a depression subtype linked to body clock disruption, with distinct symptoms and genetic markers. A new Australian study… - Keywords: circadian depression, depression subtype, university of sydney, brain and mind centre, mental health, sleep disorders, circadian rhythm, psychiatric research, antidepressants, light therapy, news, politics - Source: Abc — https://abc.net.au/news/health/2026-10-21/circadian-depression-clinical-genetic-implications/107261644 - Published: 2026-10-20T23:01:00+00:00 - Read time: 2 min - Topics: circadian depression, depression subtype, university of sydney, brain and mind centre, mental health, sleep disorders, circadian rhythm, psychiatric research, antidepressants, light therapy, news, politics ## New depression subtype identified A new Australian study published in The British Journal of Psychiatry suggests about one in four people with severe, recurrent or persistent depression have circadian depression. ## What circadian depression looks like Researchers at the University of Sydney's Brain and Mind Centre found two thousand six hundred and four people in a group of eleven thousand three hundred and eighty met criteria for circadian depression. ## Six key symptoms People with circadian depression self-reported three or more of: waking up very tired, being a night owl, seasonal illness patterns, sleeping later, sleeping more when depressed, or social jet lag. ## More severe symptoms overall Patients with circadian depression reported more severe mental health symptoms than those without it, including earlier age of onset, mania, suicidality, weight gain and more complex mental health trajectories. ## Different genetic profile The research suggests people with circadian depression may have a different genetic profile to those without it, including a higher genetic risk for attention deficit hyperactivity disorder. ## Linked to body's internal clock Circadian depression is linked to the body's twenty four hour internal clock which regulates the sleep wake cycle, mood, metabolism, concentration and many other key factors. ## Scepticism from other experts Philip Mitchell, scientia professor of psychiatry at UNSW who did not contribute to the research, said more research was needed before circadian depression could be classified as its own subtype. > At the moment it's not reaching the bar where this could enter clinical practice, but I think this is very thought-provoking for the field. ## Overlap with existing conditions Professor Mitchell said there was overlap between circadian depression features and atypical depression, a recognised subtype, indicating the need for clearer distinction between the two. ## Potential treatment approaches Patients with circadian depression may be less responsive to traditional antidepressants. Targeted treatments such as melatonin, melatonin targeted antidepressants, light therapy and behavioural changes may improve outcomes. ## Sam Hockey's lived experience Sam Hockey, who experienced post traumatic stress disorder and insomnia from age eight after a house fire, now works as a youth lived experience researcher and co authored the study. ## What helped Hockey manage symptoms Learning about circadian patterns and making behavioural changes, such as putting his bedside light on a timer, helped Hockey regulate his body clock after more than two decades of mental health struggles. > understanding more about his twenty four hour internal clock earlier in life would have saved a lot of grief, a lot of trouble, a lot of money, and hardship. ## Next step: ask patients about circadian patterns Experts agree there is enough evidence to warrant asking patients with depression about their circadian patterns, in addition to, not instead of, traditional treatment options. > It's important to address the sleep and circadian complaints in patients that are presenting with psychiatric disorders, including depression, as well as treating the depression symptoms. ## Key takeaway A new Australian study suggests about one in four people with severe depression have circadian depression, a proposed subtype linked to the body's internal clock, with implications for targeted treatment.