Are wearables the new gold standard in sleep and heart monitoring?

Wearable devices have become increasingly popular for monitoring sleep, heart rate, and heart rate variability, promising convenient and continuous health tracking. This study aimed to validate six commonly used wearable devices—Apple Watch S6, Garmin Forerunner 245 Music, Polar Vantage V, Oura Ring Generation 2, WHOOP 3.0, and Somfit—against the gold-standard assessments of polysomnography (PSG) and electrocardiography (ECG) in healthy adults.
The study included 53 participants who spent a night in a sleep laboratory while wearing all six devices, alongside PSG and ECG equipment. The findings revealed varying degrees of accuracy among the devices in detecting sleep stages and heart metrics. For two-state categorization of sleep (sleep or wake), the wearables showed high agreement with PSG, with accuracy rates ranging from 86% to 89%. The Oura Ring Generation 2 and WHOOP 3.0 demonstrated the highest agreement. However, for multi-state categorization of sleep (specific sleep stages), the agreement was lower, indicating that while these devices can reliably measure overall sleep duration, they struggle with differentiating between sleep stages. In terms of heart rate and heart rate variability, the wearables showed good to excellent correlation with ECG-derived measures. The Apple Watch S6 and Oura Ring Generation 2 had the highest accuracy for heart rate. For heart rate variability, the devices generally underestimated the values compared to ECG, with varying degrees of bias and limits of agreement.
These results highlight the potential and limitations of current wearable technology. While they provide a convenient alternative for continuous monitoring, particularly for overall sleep duration and heart rate, improvements are needed in their accuracy for sleep staging and heart rate variability.