Overview
- The study, published in the British Journal of Psychiatry on Oct. 21, analyzed clinical and genetic data from 11,380 Australians with severe, recurrent or persistent depression and found about 2,604 people met the researchers’ circadian criteria.
- Researchers defined the proposed subtype by features such as marked morning sleepiness, delayed sleep timing, social jet lag, excessive sleep during episodes, and seasonal shifts in mood.
- People meeting the criteria had earlier illness onset, worse symptoms, lower reported benefit from common antidepressants like SSRIs, and higher genetic risk scores linked to ADHD and mood disorders.
- Authors argue the pattern points to a partly distinct biology and suggest clock‑targeted options — light therapy, sleep timing strategies and melatonin trials — could be tested earlier for this group.
- Outside experts caution the results are exploratory because the study used self‑reported sleep measures, sampled mainly people of European ancestry, lacked objective circadian tests, and needs replication and randomized trials before changing practice.