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From Raw HRV Data to Actionable Insights: Introducing Spike Stress Score
October 14, 2025
3
min
Quick Learnings
In today’s world, stress isn’t just a personal struggle anymore; instead, it’s quickly becoming a core expectation for wellness, health, and fitness apps and platforms. Reports show that 7 out of 10 adults in the U.S. report experiencing stress regularly, more and more people are using wearable devices daily, and mental health apps are projected to reach $23.8 billion by 2032. However, when trying to integrate stress measurements, developers face the problematic fact that every wearable device measures stress differently.
Garmin reports “stress” as deviations in heart rate variability (HRV), Fitbit uses proprietary readiness algorithms, Apple provides HRV raw values without a stress label, and others rely on skin conductance or respiratory rate. For developers, this not only means building and maintaining custom integration for each device, but also creating your own scoring system, a costly and time-consuming process.
Clearly, the demand is there, and users want to track their overall well-being, not just steps and workouts. Yet, those building wellness-focused apps lack a unified way to interpret stress across devices.
Spike Stress Score solves this by converting raw data from any device into a single, unified score from 0 to 100. We use the same formula to calculate the Stress Score across all supported devices, so no matter which wearable your users have, they will receive their stress score based on the same logic. With the Spike Wearables API, you also get Spike Health Insights that include unified Stress, Sleep, Activity, and Readiness scores, improving the value proposition for your users, without building custom logic for each device.
Main metrics that measure stress
Wearable devices cannot directly measure cortisol levels (the primary stress hormone), but they can detect physiological responses to stress. The most relevant metrics are:
- HRV. Heart rate variability refers to the slight time differences between each heartbeat. A higher HRV indicates higher parasympathetic (rest and digest) activity, while a lower HRV indicates higher sympathetic (fight or flight) activity. Thus, high HRV reflects lower stress. It is highly reliable and recognised as a biomarker for the autonomic nervous system activity in clinical and athletic contexts.
- Heart rate (HR). Cortisol increases your heart rate, preparing the body for fight or flight, making it a straightforward stress-related metric. The rate of HR recovery after a stress event is a strong indicator of parasympathetic function and stress resilience.
- Breathing rate. The same mechanism that increases the HR also increases the respiratory rate, making them closely tied. Wearable devices estimate breathing rate by detecting small changes in heart rate and body movement that occur with each breath.
- Blood oxygen saturation (SpO2). Stress cannot directly affect blood oxygen saturation, but hyperventilation, which can be caused by stress, can lead to poor oxygen exchange in the lungs, lowering SpO2. However, it should not significantly vary in healthy individuals.
Spike API turns raw metrics into a single, unified Stress Score (0-100). The higher the score, the higher the stress. The Stress Score is part of Spike Health Insights, adding measurable value to your product by delivering a unified, easy-to-interpret wellness metric. This plug-and-play integration reduces engineering overhead, accelerates development, and lets you focus on core app features while gaining a clear competitive edge.
How can health apps leverage a unified Stress Score?
Introducing a unified Stress Score can provide significant product leverage. Developers building with wearable data could use Stress Score to evaluate pre vs. post-treatment stress objectively, measure stress changes over time, and for other application-specific uses.
Mental Health & Wellness Apps
Stress Score can be used to measure the effectiveness of the meditation and breathwork sessions by comparing the Stress Score before and after sessions. This can be used to deliver personalized recommendations for stress management, increasing engagement, and revenue.
Fitness & Performance Apps
A unified Stress Score could enable tracking the correlation between exercise intensity and stress response and suggest when more recovery may be needed. Apple HealthKit already has a similar idea, tracking overall activity load. Stress Score could also be combined with training load and Sleep Score to provide personalized recovery insights. This could help detect potential overtraining, crucial for apps focusing on athletes.
Adding additional features like a Stress Score to your fitness app could allow you to send personalized notifications, like “take a quick breathing session” or “time to destress”. The benefits are evident from Longevo, which has increased its user engagement by 15% after implementing the Spike Wearables API.
Corporate Wellness Platforms
Stress Score would enable employee stress trend monitoring, making it possible to identify early signs of burnout before they escalate. This can be utilized to take preventative measures such as micro-breaks, breathing sessions, bonus days off, or other initiatives.
This can be particularly important for high-stress professions such as first responders, healthcare workers, or military personnel, where chronic stress and burnout can directly impact performance, decisions, and long-term health.
FirstNet, a nationwide public safety communications platform developed with AT&T, has emphasized the importance of monitoring and addressing the stress levels of first responders. Its recent wellness initiative highlights the growing demand for data-driven mental health and resilience tools, reinforcing the need for unified stress metrics like the Spike Stress Score to support proactive workforce wellbeing programs.
Medical Research & Clinical Applications
Spike’s Stress Score allows clinical and research platforms to get a unified stress metric, enabling simpler data collection for population studies. It also enables tracking long-term stress patterns or measuring stress changes post-treatment.
There are already studies looking into tracking HRV through wearable devices to measure stress; however, for larger studies or meta-analyses, the lack of unified scoring could pose a serious challenge of manually entering stress-related data, which could be solved by the ready-to-use Spike Stress Score.
Part of Spike Health Insights
The Stress Score is one of the four scores within Spike Health Insights — a plug-and-play solution you can simply add onto your app without building or maintaining device-specific logic. Health Insights are included from our Tier 2 package and involve: Sleep, Stress, Readiness, and Activity Scores.
This allows you to stay focused on your app’s core features, while our Wearables API handles the complexity of aggregating and validating data across devices and platforms, allowing you to unlock actionable health insights faster. You do not need to invest time or resources in developing provider-specific integrations and their upkeep. The result: faster time-to-market, lower engineering costs, and a stronger value proposition for your users.
Available now
The Spike API Stress Score is available as part of Spike Health Insights for Tier 2 clients and above. It can be accessed through standard API endpoints by following our developer documentation. Additionally, each client gets a dedicated implementation engineer for additional support.
If you want to add a Stress Score to your app, schedule a personalized demo to discuss how to strengthen your product offering and deliver more value to your users with Spike 360° Health Data API.
References
Besson, C., Baggish, A. L., Monteventi, P., & et al. (2025). Assessing the clinical reliability of short-term heart rate variability: Insights from controlled dual-environment and dual-position measurements. Scientific Reports, 15, 5611. https://doi.org/10.1038/s41598-025-89892-3
Cowley, D. S., & Roy-Byrne, P. P. (1987). Hyperventilation and panic disorder. The American Journal of Medicine, 83(5), 929–937. https://doi.org/10.1016/0002-9343(87)90654-1
Dalmeida, K. M., & Masala, G. L. (2021). HRV Features as Viable Physiological Markers for Stress Detection Using Wearable Devices. Sensors, 21(8), 2873. https://doi.org/10.3390/s21082873
Epel, E. S., Crosswell, A. D., Mayer, S. E., Prather, A. A., Slavich, G. M., Puterman, E., & Mendes, W. B. (2018). More than a feeling: A unified view of stress measurement for population science. Frontiers in Neuroendocrinology, 49, 146–169. https://doi.org/10.1016/j.yfrne.2018.03.001
Jerath, R., Syam, M., & Ahmed, S. (2023). The Future of Stress Management: Integration of Smartwatches and HRV Technology. Sensors, 23(17), 7314. https://doi.org/10.3390/s23177314
Li, K., Cardoso, C., Moctezuma-Ramirez, A., Elgalad, A., & Perin, E. (2023). Heart Rate Variability Measurement through a Smart Wearable Device: Another Breakthrough for Personal Health Monitoring?. International Journal of Environmental Research and Public Health, 20(24), 7146. https://doi.org/10.3390/ijerph20247146
Thau, L., Gandhi, J., & Sharma, S. (2025). Physiology, Cortisol. (Updated 2023 Aug 28). In: StatPearls (Internet). Treasure Island (FL): StatPearls Publishing; 2025 Jan–. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538239/
FAQs
What is Spike Health Insights?
Spike Health Insights are part of the 360° Health Data API. It provides unified 0-100 scores for Activity, Stress, Sleep, and Readiness. Developers can add this plug-and-play feature to integrate health insights into their app.
What is a Spike Stress Score, and why does my app need it?
Spike Stress Score converts raw data from any wearable device into a single 0-100 score. This saves development time, reduces engineering costs, and provides your users with a reliable way to track stress regardless of which device they wear.
Which wearable devices are supported by the Spike API?
Spike API supports over 500 devices and fitness apps. Because we handle the device-specific integrations, you don't need to worry about maintaining compatibility with each manufacturer's proprietary metrics or APIs.
What's the ROI of adding a Spike Stress Score to our app?
Apps that add the Stress Score or other Health Insights tend to see increased user engagement, higher retention rates, and a competitive advantage. For example, Longevo increased user engagement by 15% after implementing Spike's Wearables API. Beyond engagement metrics, you'll reduce engineering costs by avoiding device-specific development and maintenance. Stress tracing can also open new opportunities for wellness, fitness, and other health apps.
What other health metrics come with the Spike Stress Score?
The Stress Score is part of Spike Health Insights, which includes four unified scores: Stress, Sleep, Readiness, and Activity. All are included in our Tier 2 package and above. In essence, you get comprehensive wellness tracking from over 500 wearable devices with a single API, creating a complete 360° health data solution for your users without building separate logic for each metric.
How are health scores better than raw data for end users?
Spike Health Insights are easy to understand, comparable, and actionable for end users. They get a 0-100 score about their sleep, stress, readiness, and activity, instead of being overwhelmed with different metrics such as heart rate, HRV, VO2 max, and numerous others.
How do I get started with Spike Stress Score?
Our Stress Score is available for those using Tier 2 Spike Wearables API and above. You will be able to access it through standard API endpoints, with full developer documentation provided. To further support integration, a dedicated implementation engineer will be assigned to every client.
