What the stress index is and how it is calculated

There is no thermometer for stress. VertigoMe looks at how your heart is behaving and turns that into one number between 0 and 100.

What the number means

• Lower numbers mean your body looks calm and rested.
• Higher numbers mean your body looks more strained than usual.

There is no number to aim for. What matters is how today compares with your own usual.

Where it comes from

It is built from two things your watch or ring already tracks: your resting heart rate and your HRV. These come from a connected WHOOP, Oura, Polar or Garmin, or from Apple Health or Health Connect.

If your stress source is a Garmin watch or an Oura ring, the device works out its own stress number and VertigoMe shows that instead.

How the maths works

1. VertigoMe looks at your previous two weeks of resting heart rate and HRV to learn your usual range. It needs at least five days of each first.
2. It uses a careful way of measuring "usual" that is not thrown off by one odd day.
3. Today's numbers are compared with that range. A higher resting heart rate and a lower HRV both push the score up. Resting heart rate counts slightly more.
4. The result is scaled to 0 to 100.

So your 70 and someone else's 70 do not mean the same thing.

How it is used

Stress high (above 75) and Stress low (below 10) are automatic triggers under Manage Items, Triggers. When one fires, it counts in your risk score, and Insights can show whether it lines up with your spins. Stress you feel without a watch can be logged by hand with the Stress event or Anxiety spike triggers.

Where to see it

1. Tap the Monitor tab.
2. Scroll to the Cognitive card. The stress index sits there with the noise reading (and screen time on Android).

If it is empty

The stress index needs both resting heart rate and HRV. In Data and Notifications, Stress index can only be switched on once HRV and Resting heart rate are on.

A reminder

A high number is not a verdict on your day. It just means your body is showing signs of strain. To turn it off, open the gear icon, Data and Notifications, Cognitive, and switch off Stress index.