CASE REPORT article
Front. Psychiatry
Sec. Digital Mental Health
Volume 16 - 2025 | doi: 10.3389/fpsyt.2025.1695158
This article is part of the Research TopiceHealth and Personalized Medicine in Mental Health and Neurodevelopmental Disorders: Digital Innovation for Diagnosis, Care, and Clinical ManagementView all 10 articles
Wearable-Derived Heart Rate Variability and Sleep Monitoring as Predictors of Mood Episodes in Bipolar Disorder: A Case Report
Provisionally accepted
- 1TechDoctor Inc., Tokyo, Japan
- 2Research Center for Child Mental Development, Chiba University, Chiba, Japan
- 3Sakakibara Occupational Health Partners Co., Ltd., Tokyo, Japan
- 4Division of Rheumatology, Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
- 5Division of Rheumatology, Department of Medicine, NHO Tokyo Medical Center, Tokyo, Japan
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Background: Bipolar disorder is a chronic psychiatric condition characterized by alternating episodes of mania and depression, and the prediction and management of mood episodes remain significant clinical challenges. Traditional assessments of mood states have largely relied on subjective methods, such as clinical interviews and self-report questionnaires, which present limitations in terms of early detection and timely intervention. Recently, physiological and behavioral data obtained from wearable devices—particularly heart rate variability (HRV) and sleep parameters—have been proposed as potential digital biomarkers, offering novel opportunities for objective clinical evaluation. Case Presentation: We conducted a single-case study involving a man in his 40s diagnosed with bipolar disorder, who continuously recorded HRV and sleep parameters using a wearable device over approximately eight months. These data were analyzed in relation to self-reported mood scores. The findings revealed that reductions in nocturnal RMSSD preceded the onset of depressive symptoms, while decreases in time spent in bed were significantly associated with the exacerbation of manic symptoms. In contrast, no clear associations were observed between daytime HRV or activity measures and mood scores. Conclusion: This case study suggests that continuous monitoring of objective physiological measures, such as HRV and sleep parameters, may serve as useful digital biomarkers for predicting mood episodes and preventing relapse in bipolar disorder. Future research involving larger samples and the development of predictive models will be essential to advance the clinical application of these novel assessment approaches.
Keywords: Bipolar Disorder, Heart rate variability, digital biomarker, wearable devices, Mood episodes, Sleep monitoring, case study, Depression
Received: 29 Aug 2025; Accepted: 23 Oct 2025.
Copyright: © 2025 Eto, Mochizuki, Fukami, Sakakibara and Izumi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Keisuke Izumi, izz@keio.jp
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