How Can a Smartwatch Can Detect Depression Risk?

Summary: A smartwatch can identify current mental health states and assess depression risk by collecting physiological data associated with patterns of behavior that increase risk of depressive symptoms.

Key Points:

• Korean researchers used smartwatch data to identify circadian rhythms – i.e. patterns of sleeping and waking – among shift workers
• Researchers developed a model that uses changes in circadian patterns to predict next-day depressive symptoms
• The research team suggests systematic use of smartwatch data can streamline the current depression assessment, referral, and treatment paradigm

Smartwatch and Depression Risk: Effective for More Than Work Emails

Living in the modern world means we often engage in behaviors that run counter to our natural patterns of sleeping, waking, rest, and activity collectively known as our circadian rhythms. These behaviors include things we want to do, such as staying up late watching movies or socializing, and things we may not want to do, such as overnight shift work, or work that keeps us up past when we’d prefer – and when our circadian clocks urge us to lay down and get rest.

Research shows that disruption to circadian rhythms may contribute to the worldwide increase in mental health disorders such as anxiety, depression, and others. Consider these figures on global mental health published by the World Health Organization (WHO):

• 300 million people have an anxiety disorder
• 280 million people have a depressive disorder
• 39 million people have bipolar disorder
• 24 million people have schizophrenia

In light of that data, to say mental health is a serious public health issue, worldwide, would be a significant understatement. That’s why a group of researchers in Koreas launched an investigation designed to improve mental health monitoring and surveillance – the good kind of surveillance – with a non-invasive, easy-to-use method: a smartwatch.

Smartwatches: A Non-Invasive Method for Collecting Health Data

In the study “The Real-World Association Between Digital Markers of Circadian Disruption and Mental Health Risks,” researchers from Korea leverage expert advice from the WHO that suggests studying circadian disruption may be a key step in understanding the increase in mental health disorders worldwide, as demonstrated in the figures we share above.

In Korea, a significant increase in mental illness followed the COVID-19 pandemic. Over the past five years, prevalence of clinical mental illness increased by 37 percent. However, the desire to study the role of circadian disruption in this increase is constrained by practical considerations:

• Measuring circadian rhythms involves drawing blood and saliva samples every 30 minutes over a 24-hour period
• Measuring sleep cycles requires polysomnography, e.g. the recording and study of brain waves, blood oxygen levels, and heart rate during sleep
• This requires a hospital stay, specialized equipment, and medical staff

The cost of recurring blood and saliva tests, alongside polysomnography at $1,000 per session, puts large-scale studies on circadian disruption – necessary for reaching population-level conclusions about prevalence and treatment – out of reach for most mental health researchers.

That’s where smartwatches – and an innovative new method research method – enter the discussion.

Studying sleep patterns is expensive, as we can see above. Studying circadian disruption is complex, because it involves defining typical rhythms, which are specific to every individual, identifying disruptions to those rhythms, also unique to each individual, then determining whether disruptions are caused by individual behavior, dysfunctional internal processes, or some combination of both. Therefore, studying circadian disruptions in just one person is a challenging undertaking by itself.

To overcome this challenge, researchers developed an algorithm that accurately estimates circadian patterns in an individual and creates an objective digital twin which scientist can use to compare daily – and nightly – real time smartwatch data to detect circadian disruption.

Smartwatch, Circadian Rhythm, and Depression Risk

Researchers recruited 800 shift workers – physicians in training, who regularly engage in behaviors that don’t match natural circadian cycles – and equipped them with smartwatches, then collected over 50,000 days of data over the study period. To measure circadian rhythms and disruptions, researchers used standard sleep metrics such as time in sleep, time in REM, and heart rate. To measure mental health symptoms, participants completed the Patient Health Questionnaire-9 (PHQ-9).

Here’s what they found:

Three distinct circadian disruptions correlated with and accurately predicted the incidence of six symptoms the following day:

1. Sleep problems
2. Low mood/low self-esteem
3. Change in appetite
4. Restless/fidgety, or the opposite, slow movement and affect
5. Impaired concentration
6. Suicidal thoughts

Since all six of those symptoms are also symptoms of depression, the research team views this as a breakthrough in mental health treatment. Here’s how Dr. Daw Wook Kim, a lead researcher on the study, describes these findings:

“This is expected to present a new paradigm for mental health care. By resolving some of the major problems socially disadvantaged people may face in current treatment practices, they may be able to take more active steps when experiencing symptoms of depression.”

That observation surprised us: this is a way to level the playing field for mental health care, including assessment, surveillance, and treatment. If an inexpensive smartwatch and a free app – which is under development by the research team – can accurately predict both symptoms and mood for the next day, then in the near future, patients with less-than-adequate access to resources can streamline the assessment process, present smartwatch data to providers, and engage in psychotherapy to address their mental health symptoms.

That’s a new approach – and it could work. We’ll keep an eye out for any new developments in this technology, and report them here as soon as we learn anything new.

Finding Help: Resources

If you or someone you know needs professional treatment and support for a mental health disorder, please contact us here at Crownview Psychiatric Institute: we can help. In addition, you can find support through the following online resources:

• The National Alliance on Mental Illness (NAMI): Find a Professional
• The National Institute of Mental Health (NIMH): Finding Treatment
• The Substance Abuse and Mental Health Services Administration (SAMHSA): Finding Help
• American Psychiatric Association (APA): Treatment Locator
• SAMHSA: Early Serious Mental Illness Treatment Locator