myRhythmWatch

Functionality & Mechanism

myRhythmWatch is a mobile health platform developed for the passive quantification of 24-hour rest-activity rhythms (RARs). The system captures raw accelerometer data through a continuously worn Apple Watch for a minimum of three days. This data is synchronized via HealthKit and Bluetooth to a web-based service where nonparametric and extended-cosine RAR variables are computed. The interface then visualizes these metrics, providing a longitudinal assessment of rhythm stability, amplitude, and fragmentation to facilitate rhythm monitoring.

Evidence & Research Context

• A validation study (N=23) comparing Apple Watch data to a research-grade ActiGraph device demonstrated good-to-excellent consistency (ICC=0.84) and strong correlations (Spearman R=0.7–0.9) for key rest-activity rhythm metrics.
• A pilot feasibility study (N=40) in older adults, including individuals with mild cognitive impairment (MCI), confirmed the system is a viable and acceptable tool for longitudinal data collection in this population.
• In the same pilot study, specific rhythm characteristics, such as fragmentation and activity onset timing, were significantly associated with neuropsychological performance on memory and processing speed tasks.
• The platform was designed to provide a scalable, real-time method for circadian rhythm assessment, addressing the practical limitations of traditional actigraphy for large-scale research and clinical applications.

Intended Use & Scope

This platform is intended for researchers and clinicians for the longitudinal assessment of rest-activity rhythms. It serves as a tool for risk factor characterization and monitoring, not for clinical diagnosis. The derived metrics are device-specific and should not be directly compared with values from other actigraphy systems. Interpretation requires professional context and is not a substitute for clinical evaluation.