New research from McMaster University suggests wrist-worn devices such as smartwatches can signal when someone recovering from major depressive disorder (MDD) is at increased risk of relapse by monitoring sleep and activity patterns. The study, published in JAMA Psychiatry, found that wearable-derived measures could predict relapse weeks or months before symptoms return.
MDD, also called clinical depression, is a common condition characterized by persistent sadness and loss of interest that affects mood, behavior, and physical functioning. Up to about 60% of people with MDD will experience at least one relapse in their lifetime.
The study followed 93 adults across Canada who had recovered from depression. Participants wore research-grade actigraphy devices (similar to commercial Fitbits or Apple Watches) for one to two years, producing more than 32,000 days of sleep and activity data. Researchers analyzed longitudinal patterns to identify signals that preceded relapse.
Key findings:
– People with the most irregular sleep patterns had nearly double the risk of relapse.
– The strongest predictor was a reduced difference between daytime activity and nighttime rest (relative amplitude).
– Increased time awake during the night after initially falling asleep predicted higher relapse risk.
– Individuals’ sleep schedules became more erratic in the period leading up to a relapse.
The authors and outside experts highlighted the potential of continuous, passive monitoring to fill gaps between clinical visits. Benicio Frey, MD, a study co-author, said advances in digital technology and AI could enable tools that warn users weeks in advance and prompt clinical contact. Alex Dimitriu, MD, noted that long-term wearable tracking can reveal subtle, otherwise hard-to-detect patterns and that variance in sleep was an effective predictor in this study.
Therapist Rod Mitchell described sleep disruption as an early biological warning signal distinct from current mood ratings, comparing a wearable to a seismograph that detects tremors before a larger event. Sarathi Bhattacharyya, MD, a sleep specialist, added that sleep-tracking data can inform provider decisions and that many commercially available devices already market sleep monitoring features.
Decades of research show a bidirectional relationship between sleep and depression. Insomnia is a common and modifiable risk factor: sleep problems occur in 80% to 90% of people with depression, and having insomnia can roughly double the risk of developing depression. This study reinforces the idea that treating and tracking sleep could help prevent relapse.
MDD symptoms can include persistent sad or empty mood; irritability; hopelessness; loss of interest in activities; guilt or worthlessness; difficulty concentrating; fatigue or slowed movement; appetite or weight changes; physical aches without clear cause; and thoughts of death or suicide. Diagnostic criteria require symptoms most of the day, nearly every day, for at least two weeks. Not everyone experiences all symptoms or in the same way.
The researchers propose that wearable-derived alerts could help health systems target care to those most at risk, potentially improving outcomes and reducing the burden of recurrent episodes. For individuals, prioritizing and optimizing sleep remains a recommended strategy for supporting mental health.
If you are experiencing persistent symptoms of depression, consider speaking with a mental health or healthcare professional.
