What is the frequency of automatic measurements by StressWatch? Can I measure manually?

What is the measurement frequency of the Apple Watch? Can I control it?

Under normal circumstances, the Apple Watch will automatically measure your HRV (Heart Rate Variability) every 2 to 5 hours. If your watch is in low battery mode or if you have started a workout, it won't automatically monitor your HRV during these times. Therefore, the actual frequency of data collection can vary based on your daily activities.

Currently, the frequency of HRV monitoring by the Apple Watch is determined by the device itself. [Note] As developers, we do not have the ability to adjust the monitoring frequency of the Apple Watch.

However, for users in most countries (except mainland China), you can force your Apple Watch to check your HRV every 15 minutes to increase the monitoring frequency by:

  1. Turning on the AFib (Atrial Fibrillation) history feature in the Apple Health app under Heart.
  2. Then enabling AFib History in the Watch app under Heart section.

Be aware that this method will consume more battery than usual, cannot be enabled in mainland China, and is currently the only way to increase the HRV monitoring frequency of the Apple Watch.

Can manual measurements be triggered?

If you need to measure your current HRV value, you can trigger a measurement using the "Mindfulness" - "Breathe" feature.

Follow these steps:

  • Open the "Breathe" session in the "Mindfulness" app on your Apple Watch.
  • For accurate measurements, we recommend selecting a breathing duration of 3 minutes or longer.
  • Press start, ensure the watch is properly fitted, and try not to move your body. Keep calm, breathe naturally without following the breathing guide.
  • After completing the session, lock and then unlock your iPhone.
  • Wait about a minute, and the StressWatch will receive your data and display it.

Note: Due to Apple Watch limitations, there might be instances where data cannot be immediately returned. Please be understanding.

If your data doesn't return right away, you might want to set your phone aside and check back later in StressWatch.

Why doesn't the data update immediately after manual measurement?

If your data hasn't updated more than half an hour after following our measurement steps, it might be due to:

  • Being in a state of movement or excitement during measurement, which may prevent the Apple Watch from recording HRV.
  • The Apple Watch being in low power mode or sleep mode.
  • Measuring too frequently in a short period.

What should I consider before manually measuring HRV?

To ensure accurate HRV values that reflect your daily state, try to avoid manual measurements under these conditions:

  • Right after intense exercise: Exercise can increase your heart rate, interfering with HRV measurement results. Wait for about half an hour for your heart rate to return to normal before measuring.
  • If you're emotionally excited or tense: Avoid measuring HRV when feeling emotionally charged, as changes in emotional state can affect the autonomic nervous system and, consequently, HRV measurements.
  • After eating, consuming alcohol, or caffeine: Avoid large meals or caffeine before measuring HRV, as they can influence your heart rate and HRV.
  • After smoking or using medication: Avoid smoking or using drugs (especially those that affect heart rate and autonomic nervous system activity) before measuring HRV, as these substances could interfere with the measurement results.

We recommend measuring your HRV within ten minutes of waking up, before any potential daily stimulants (food, coffee, exercise, various social interactions, etc.) and make it a habit.

Measuring in the natural state of waking up is an effective way to capture our true stress state and assess readiness for the new day.

Recommended measurement approach:

  • Reduce physical activity and breathe naturally.
  • If you need to use the restroom, do so before measuring.
  • Avoid drinking too much water.
  • Measure while sitting or lying down.