When will StressWatch prompt "Stress Overload"?

What types of stress do people experience? Can StressWatch detect all of them?

There are three types of stress:

  1. Physical Stress: The body's "fight or flight" stress response to pressure or danger, such as catching a cold or facing danger.
  2. Emotional Stress: Our emotional experiences, such as feeling disliked or unhappy.
  3. Cognitive Stress: The brain's perception of things, such as struggling to focus while reading or failing to solve problems.

These types of stress are interrelated and contribute to mental stress, influencing each other.

StressWatch uses HRV (Heart Rate Variability) and resting heart rate data to detect and indicate "Physical Stress" responses.

"Physical Stress" is used to measure whether the body is in a stressed state or if the autonomic nervous system is under tension. It can help understand current fatigue levels and mental stress. This is the normal reaction of the body when it is in a "fight or flight" tense state.

Simply put: The higher your HRV and the lower your resting heart rate, the more relaxed your body is. The lower your HRV and the higher your resting heart rate, the more tense your body is.

Although emotional and cognitive stress can also lead to physical stress and lower HRV, due to the complexity of the human body, StressWatch cannot detect all of your stresses (after all, StressWatch is just an Apple Watch app that can only access limited data).

When is physical stress likely to be high?

The following behaviors affect the balance of the autonomic nervous system, and after influencing HRV and resting heart rate data, StressWatch may prompt for stress overload or suggest paying attention to stress:

  • High mental stress: High mental stress significantly lowers HRV and increases resting heart rate.
  • Physical fatigue: Insufficient or poor-quality sleep, overexertion, excessive exercise without rest.
  • Illness: HRV significantly decreases in the early stages or during illness but will recover after the body heals.
  • Dehydration: Thirst or high salt intake, it's recommended to drink about eight cups of water a day.
  • Unhealthy or irregular diet: Eating large amounts of fats or carbs, heavy-tasting food, or eating too much at night can affect HRV.
  • Alcohol, caffeine, and tobacco: These stimulants have a nervous-suppressing effect that significantly affects HRV.
  • During or after exercise: Physical stress is higher during or immediately after exercise, focusing more on the sympathetic nervous system, leading to temporary imbalance. However, moderate exercise with good rest can help improve HRV over time. Please continue to stick with it.

With the exception of the last point, all other scenarios are signals that the body or mind is in a tense state.

When prompted with low HRV and stress overload, consider slowing down and reflecting on whether any of the above situations apply. Taking action to improve can lead to a healthier, more relaxed life.

Data Update Notes

HRV Data

With normal Apple Watch usage, the Apple Watch will automatically measure HRV values every 2-5 hours, and heart rate is measured every minute.

If your watch is in any of the following states, it will not automatically monitor HRV values:

  • Watch is in low battery mode
  • Exercise mode is turned on
  • Moving at high speed (running, cycling, riding in a car, etc.)
  • Watch is not unlocked
  • Watch is not securely worn
  • WatchOS version is too old (watchOS 7 or earlier)

Therefore, the actual data collection situation may vary depending on your daily status.

If you have more questions about HRV update frequency, refer to: What is the frequency of automatic measurement in StressWatch? Can I measure manually?

Real-time Stress Data

Real-time stress is based on past heart rate and HRV data, and is updated every 6 minutes under normal conditions.

If your watch is in any of the following states, it will not update real-time values:

  • Watch is in low battery mode
  • Exercise mode is turned on
  • Walking
  • Moving at high speed (running, cycling, riding in a car, etc.)
  • Watch is not unlocked
  • Watch is not securely worn
  • WatchOS version is too old (watchOS 7 or earlier)

Also, Apple Watch face refresh rates are limited by watchOS and won't update in real-time.

Tips

Tip 1: HRV does not equal mental stress

Note, even though mental stress can influence HRV values, HRV does not equal mental stress.

Any statement equating HRV to mental stress is incorrect, as HRV is influenced by mental stress, physical fatigue, stimulants, age, genetics, and other factors. It should be considered individually in different scenarios.

Understanding the relationship between HRV, physical fatigue, and mental stress is the first step in making good use of this valuable body metric recognized by the sports community.

Feel free to click the hamburger menu in the top left to read more, or follow our Xiaohongshu account @StressWatch App, where we update relevant research papers and popular science to help you better understand heart rate data and use it to guide your life.

Tip 2: It's normal for HRV to fluctuate during the day

It's perfectly normal for HRV to fluctuate significantly throughout the day. There's no need to over-focus on a single measurement result.

We recommend observing multiple consecutive measurements and checking the "Overall Stress Status for the Day" on the StressWatch app's homepage. Multiple measurements provide a more accurate reading.

Tip 3: HRV is highly personalized and requires some time with the watch

HRV is a very personalized metric. Therefore, on a new watch without sufficient personalized data (less than 30 days of heart rate data), it may not be accurate.

Please continue wearing the watch; StressWatch's personalized stress algorithm will learn more about you over time.