Scripps Research study links sleep variability with sleep apnea and hypertension How consumers' digital activity trackers could enable personalized health screening and early intervention for cardiovascular health and beyond.December 23, 2025
LA JOLLA, CA Over 70 million Americans wear digital activity trackers (DATs) to record their sleep, steps and heart rate. A new study from Scripps Research found that these devices could also provide insight into even more, including individual health risks like obstructive sleep apnea (OSA) and high blood pressure.
The findings, published in the Journal of Medical Internet Research on December 3, 2025, used DATs to identify an association between sleep variability the night-to-night fluctuation of when an individual falls asleep and wakes and their risk of developing sleep apnea and hypertension. This research joins a growing body of evidence that DATs could become more useful clinical tools to assess health risks in the near future.
Data from digital activity trackers provides a unique way to detect meaningful health patterns from the devices that people already own, says Stuti Jaiswal, senior author and assistant professor at Scripps Research, who is also a faculty hospitalist at Scripps Clinic. Digital health studies have been gaining acceptance over the past decade, and we're now demonstrating what these technologies can reveal about how sleep influences cardiovascular health.
The implications of these findings are far reaching. Sleep apnea a disorder in which the airway muscles relax and collapse during sleep, causing repeated pauses in breathing impacts an estimated 50 million Americans and puts them at risk for hypertension, atrial fibrillation, heart disease and stroke. Similarly, high blood pressure (also known as hypertension) affects nearly half of Americans over 18 and elevates their risk for heart attack or heart failure. Using DATs to detect the risk of developing these conditions could allow individuals to seek treatment sooner and potentially prevent severe cardiovascular diseases.
Jaiswal and her team recruited over 1,000 adults from across the U.S. to join a sleep-focused, smartphone-based study called the Research Framework for Exploring Sleep Health (REFRESH). REFRESH was developed by sleep medicine researchers and clinicians at Scripps Research Digital Trials Center to establish how longitudinal sleep impacts different aspects of physical and mental health. For this study, nearly 400 individuals submitted an average of two years' worth of sleep data collected by their DAT and completed health-related surveys that assessed the risk of sleep apnea and identified their proclivity to being an early riser or night owl. Surprisingly, about 40 percent of individuals identified as night owls. Participants were selected for analysis based on the amount of data available on their DAT and the type of DAT they used. Though the REFRESH platform was compatible with Fitbit, Apple Watch, Garmin, and Oura devices, the study focused on Fitbit data because most participants used this device and it's the most studied wearable in sleep research.
Jaiswal and her team found that people whose sleep varied by just one hour from night to night going to bed at 11 p.m. instead of a routine bedtime of 10 p.m., for example had more than twice the risk of sleep apnea and were 71 percent more likely to have high blood pressure. This robust association suggests that digital studies have the potential to uncover distinct and clinically meaningful patterns when used over significant periods of time. It's worth noting, however, that this compelling association between sleep variability and increased risk of sleep apnea or hypertension requires further investigation into the specific cause of the association.
A significant strength of DATs is the ability to capture large amounts of data across time, describes Natalia Orendain, first author and professional scientific collaborator at Scripps Research. Our study continues momentum toward a future of potentially using consumer wearables for early disease detection and prevention.
Most people focus on sleep duration, such as getting seven to nine hours nightly. However, studies like Jaiswal's are part of the mounting evidence that irregular sleep patterns may contribute to drivers of cardiovascular disease such as inflammation, disrupted cortisol rhythms and metabolic dysfunction.
Right now, we're in the pattern-recognition phase, says Jaiswal. We're confirming these associations exist and understanding mechanisms. The next phase is figuring out how we can actually help people improve their health.
Individual biometrics identified by DATs could eventually play a role in clinical care to not only augment a personalized approach to sleep health, but to address modifiable health factors in general. Future research plans include using sleep data to study the relationship between sleep and mental health in diagnoses like depression and anxiety. Jaiswal hopes this research could help bring to light health risks that individuals aren't aware of leading to earlier intervention and ideally improving health outcomes.
In addition to Jaiswal and Orendain, authors of the study Digital biometrics in predicting risk for obstructive sleep apnea and hypertension: A decentralized, prospective cohort study, include Samantha Spierling Bagsic of Scripps Health and Scripps Research; Edward Ramos and Jay Pandit of Scripps Research; and Robert L. Owens of the University of California, San Diego School of Medicine.
This research was funded in part by a NIH/NCATS flagship Clinical and Translational Science Award Grant (CTSA UM1TR004407) and the Kruger-Wyeth settlement funds.
Translational Medicine Jaiswal, Stuti
