Overview
- This week researchers publishing in the British Journal of Psychiatry reported that about 23% of more than 11,000 people with prior depression fit a possible ‘circadian’ subtype marked by evening preference, morning tiredness, oversleeping and seasonal mood shifts.
- Experts say the clocks going back and shorter daylight rapidly change light exposure and routines, producing brief early-morning energy followed by harder afternoon slumps, lower alertness and mood declines.
- Light is the dominant circadian cue, so clinicians advise getting outdoor daylight soon after waking, keeping wake times regular, dimming evening lighting and doing daytime activity to help reset the body clock.
- The new subtype finding is preliminary and does not prove circadian disruption causes depression; researchers and clinicians stress replication and causal studies are needed before changing treatment guidelines.
- Past studies link evening chronotypes and night-shift work to higher depression risk, so if confirmed the circadian subtype could change how doctors personalise treatments and target interventions like bright‑light therapy.