A stress monitor app which helps avoid heart attack and stroke
According to the American Heart Association "Stress may lead to high blood pressure, .... heart attack and stroke" [1]. Is there an easy way to objectively monitor your daily stress to avoid these major heart health challenges? This post provides the answer. Let’s start from some basics.
What is Total Life Stress and how to measure it?
Total Life Stress is all of the stress someone experiences in their life: exercise, relationships, diet, sleep quality, lifestyle, environment, etc. Heart rate, hormones, blood pressure, glucose etc, react to life stresses and our autonomic nervous system tries to keep our internal systems in balance.
Scientists call the state of balance among all the body systems needed for the body to survive and function correctly homeostasis [2]. Multi year research by different teams shows that a practical, cost effective, and non-invasive way to measure the activity of the autonomic nervous system as relates to stress is to use so-called Heart Rate Variability (HRV) [3].
What is HRV?
HRV shows how the time between consecutive heartbeats changes within a period of time. If a user is stressed out, the time between heartbeats stays fairly constant. If a user is relaxed, the time between heartbeats shows higher variability. These changes in variability are quite small and can be detected by ECG devices or by sensors of your smartphone’s camera or smartwatches like Apple Watch.
Heart rate and HRV are regulated by the parasympathetic part of the autonomic nervous system. Parasympathetic system (PNS) controls the so-called ‘rest and digest’ state of the body. This is the reason why measuring HRV is an effective way to understand how our body is doing while trying to maintain a state of balance in response to different life stresses.
Are HRV and Heart Rate the same?
IMPORTANT: HRV is different from heart rate. Two people may have the same heart rate when measured over a period of time, for example 60 beats-per-minute (BPMs). Yet one of them may be very relaxed with high HRV and the other one totally stressed out with low HRV. Usually mobile apps invert HRV data to make readings more intuitive: lower stress (which corresponds to higher HRV) is linked to a higher state of relaxation. And vice versa: higher stress translates into lower HRV values.
How do stress monitor apps work?
Most of the stress monitor apps on Apple AppStore or Google Play use HRV as a mechanism to measure stress. Different smartwatches (i.e Apple Watch, Garmin, etc) record HRV data and save it to users' Apple Health account. HRV can also be captured when you measure heart rate by pressing your finger to a phone’s camera. Stress monitor apps extract HRV data from Apple Health to provide a user-friendly stress analysis. Hence these apps require access to the user's Apple Health account.
How is BreathNow's app stress monitor different from other apps?
BreathNow is a popular blood pressure app which helps users to track and lower blood pressure with the help of calming exercises like guided breathing or meditation. It was a natural progression for our team to add a stress monitor to the list of key features. It helps our users to understand what life events drive stress changes and identify calming activities which work best for them. Here is how the BreathNow apps monitor is different from other apps.
It displays easy to interpret stress data on either users iPhone or Apple Watch
It helps to understand which activities have the highest impact on stress change
Its stress measurement routine is scientifically proven
IMPORTANT: Some sophisticated medical grade equipment (usually a special version of an ECG machine) can provide deep interpretation of HRV data and split it into different indicators: i.e. different types of stress, energy level, illness risk etc. However a consumer device like a smartwatch or phone camera produces HRV data which is quite noisy and hence it is sufficient only for basic analysis. This data can NOT be used for deep analysis of stress factors. .
BreathNow shares with users stress data which can be REALISTICALLY obtained from a consumer device. We do not present confusing signals which CAN NOT BE calculated from noisy HRV data received from a smartphone or smartwatch.
The other thing to be aware of is that different people have different absolute HRV values. Two people may have similar absolute HRV values with one being stressed out and the other one fully relaxed.
Hence while using mobile apps and HRV to study someone’s stress it makes sense to focus primarily on two things: daily or weekly trends and stress difference between two closely spaced events, i.e. before a relaxation exercise and immediately after.
What is the scientifically proven Total Life Stress measurement routine?
For consistent stress measurement results for the daily graph a user needs to take HRV reading first thing in the morning: right after waking up, while seated on their bed [4]. Please note that to take an HRV reading on your Apple Watch you need to launch an Apple Breathe app. This is currently the only way to trigger an HRV measurement on Apple Watch at a specific time.
The other scientifically proven routine for Total Life Stress measurement is continuous HRV monitoring. It is available in a few specialised wearables which are paired with sophisticated AI software from the same wearables manufactures. This software filters out useful signals from noisy data and makes sense from random HRV changes throughout the day. For example as of March 2023 this combination of continued HRV monitoring and analysis is not available for Apple Watch.
How do I use the BreathNow stress monitor?
BreathNow displays stress measurement results in two ways:
A. A graph which shows a trend in stress changes. This graph shows how user stress changes from one day to another. You can make the following conclusions based on the trend of this graph:
Small variations in stress from day to day, no obvious trend observed. Most likely you properly control your stress. Congratulations!
The graph is trending up. Most likely your stress is building day to day. Try to increase quality sleep time, spend more time walking in nature, do more breathing exercises and meditations. Here is one example of a breathing exercise available in BreathNow and also on our YouTube channel. If done consistently, it produces long term positive effects.
3. The graph is trending down. This is a great opportunity to increase your energy level to be more productive. Go for a moderate intensity exercise like brisk walking, jogging, cycling or swimming. Alternatively do more Energise breathing exercises in the BreathNow app.
4. The graph shows a sudden spike in stress level after a morning measurement while you exercise as usual and do not experience any other obvious stressors (i.e. too much alcohol the night before). This may be an indication that your body is fighting some sort of acute illness, i.e. stomach or viral infection.
B. Text comments which explain how stress has changed between the two consecutive measurements. BreathNow will inform you whether your stress level increased, decreased or stayed the same after the previous measurement. This is a great way to check how particular exercises help you to calm down (breathing, meditation, stretching, etc) or energize you (aerobic exercise like jogging or cycling, Energize breathing, etc). Take a stress measurement, perform one of the exercises in BreathNow, check stress level again. This is a great way to check which particular exercise produces the best results for you.
How can I help with making the BreathNow stress monitor more accurate?
After taking a stress reading BreathNow monitor requests your feedback about the way you feel. It takes just a few seconds to mark appropriate smileys on the feedback form. Your inputs are anonymous and they help us to improve the accuracy of the stress monitor. As we analyze more user inputs, we plan to extend the functionality of the monitor to add stress prediction capability. This function will help to lower further your heart health risks by notifying in advance about approaching upper stress limits.
Summary
HRV is a practical, cost effective, and non-invasive way to measure the activity of the autonomic nervous system as relates to Total Life Stress
HRV data from consumer devices, like Apple Watch, are quite noisy and allow reliably to show changes only between days or between closely spaced measurements. Strict measurement routine should be followed to secure reliable data.
Stress monitor of BreathNow app helps to reduce heart health risks by displaying daily stress changes and helps to identify relaxation activities which work best for the user
References