Circadian Rhythm App for Depression and Bipolar

A wearable-guided app that times light exposure to the body’s clock

STUDY: Yeom JW et al, Am J Psychiatry 2026

STUDY TYPE: Randomized, double-blind, multicenter, sham-controlled trial

FUNDING: Independent

Background

Unstable timing of sleep, activity, and light exposure is linked to mood episode onset, both in bipolar and unipolar. The Circadian Rhythm for Mood (CRM) app pairs a Fitbit and phone light sensor with an algorithm from earlier Korean cohort work, flagging circadian drift and nudging patients back on schedule before a relapse builds.

This study tested it in bipolar and unipolar disorders.

The Study

• 93 adults with major depressive disorder or bipolar disorder at Korean centers (modified intent-to-treat, N=80).
• Randomized, double-blind, to the CRM app or a look-alike sham app, both added to treatment as usual, for 12 months.
• The app set an individualized light-exposure target, flagged daily instability, forecast 3-day relapse risk, and tracked mood; the sham app looked identical but gave generic feedback.

Results

The app group had roughly three times fewer relapses over the year (incidence rate ratio 3.39, 95% CI 1.19–6.40, p=0.018).

Time in episode and time to recurrence also favored the app.

Its main advice was to get bright light about 9.5 hours after estimated melatonin onset, timed to the phase shifts seen before manic and depressive episodes.

Limitations

The trial enrolled Korean patients only, leaving generalizability unclear. The corresponding author discloses a financial conflict of interest through the company that supplied the app.

Practice Implications

1. These are encouraging results. While we wait for the app, a dawn simulator can delivery that circadian-timed light, programmed to go off at the same time each morning.
2. Meanwhile, here are evidence based mental health apps available now.