Experts discover new type of depression that doesn’t respond to pills – but there’s a less risky fix

Australian researchers have proposed that disrupted sleep and wake patterns may define a depression subtype they call “circadian depression”. The idea could help explain why some patients do not benefit from standard antidepressants, and suggests that sleep-focused care may be worth considering earlier.

The study analysed data from more than 11,000 participants; 2,604, or nearly a quarter, were classified as having the subtype. Their reported features included seasonal illness, excessive sleep, persistent fatigue and being more active at night. Researchers suggested light therapy, melatonin and behavioural treatment as possible options, but outside experts questioned whether the findings establish a distinct subtype and said they do not yet justify changes to prescribing.