Smartwatches may predict a depression relapse.

A JAMA Psychiatry study of 93 recovered patients found that wearable sensors recorded irregular sleep and reduced day–night activity differences that often preceded depression relapse, based on more than 32,000 days of data.

Researchers at McMaster University reported in JAMA Psychiatry that wearable trackers detected changes in sleep and activity patterns that often came before a depression relapse. The study followed 93 Canadian adults with a prior diagnosis of major depressive disorder who had recovered from an episode. Participants wore a research-grade device similar to a commercial smartwatch and attended regular in-person assessments. Scientists analyzed more than 32,000 participant-days of continuous data to study daily rhythms. Key findings: - The study followed 93 adults with prior major depressive disorder for up to two years. - Participants wore research-grade devices continuously, producing over 32,000 days of data. - Irregular sleep schedules were associated with nearly double the risk of relapse. - Smaller differences between daytime movement and nighttime rest often preceded relapse. Summary: The study found that changes in sleep regularity and day–night activity differences often preceded relapse, suggesting that passive wearable monitoring could detect risk weeks or months in advance. The researchers noted that an "always-on" approach could allow monitoring between clinic visits. Undetermined at this time.