Early detection of depressive episodes is important because shorter duration of untreated illness is associated with better outcomes, yet routine care remains largely reactive and dependent on retrospective self-report. Wearables enable passive, continuous monitoring, and circadian disruptions in sleep-wake, activity, and diurnal heart rate (HR) patterns may precede mood episodes. However, prior wearable-based models often relied on short prediction horizons, simplistic circadian proxies, and limited clinical interpretability. We evaluated a deep learning approach that integrates two complementary circadian markers derived from a single wearable: an HR-derived cosine acrophase and a sleep-timing-based proxy measure of circadian phase related to dim-light melatonin onset (DLMO), since melatonin was not directly measured. Performance was summarized across risk-based operating thresholds. In a multicenter real-world mood disorder cohort (N = 144; 90,281 person-days), we trained a time-series model using 7-day wearable histories to predict the presence of a clinician-verified depressive episode one week ahead, with participant-level splits (6: 2:2) and discrimination consistency summarized across 10 repeated holdout runs. The combined circadian model achieved a mean area under the receiver operating characteristic curve (AUROC) of 0.772 (95% confidence interval [CI], 0.750-0.794). On the held-out test set, the top 20% of risk-ranked patient-days captured 63.5% of depressive-episode days; at a base prevalence of 5.3%, positive predictive value (PPV) was 16.7% (3.2-fold prognostic lift), with a review burden of 20 per 100 patient-days. These findings support the feasibility of wearable-based week-ahead depressive-risk stratification in mood disorders, although external validation, probabilistic calibration, transportability assessment, and prospective episode-onset evaluation are required before clinical implementation.
Circadian Biology