Alarm / Anxiety: An Experimental Index
Estimated from a single camera (PPG) reading — an educational estimate, not a medical measurement. State labels (Flow, Focus, Alarm…) are rough, experimental patterns, not emotion detection.
What this number is
Alarm here is an experimental index built from rhythm irregularity and breathing rate. It is not an anxiety test and it cannot detect fear or worry. It rises when your beat-to-beat intervals look irregular relative to their average (high CSI) and when your estimated breathing rate is above 15 breaths per minute.
How this tool calculates it
Alarm = 0.7 × Stress + 3 × (breathing rate − 15, if above 15), limited to 0–100%. Stress = 130 × CSI. Heart rate itself is not part of this formula. Breathing rate is estimated from slow swings in the pulse signal and counts as 0 when no clear rhythm is found. The tool works on a rolling 15-second window of fingertip video (about 30 frames per second), finds each pulse peak, keeps only beat-to-beat (RR) intervals between 400 and 1,500 ms that are within 22% of the median, and smooths the displayed numbers so they change gradually.
How to read it
Higher
Beat intervals varied a lot relative to their mean and/or breathing was estimated above 15 per minute. Talking, moving your finger, cold fingers or dim light can raise it as much as a stressful moment can.
Lower
The rhythm looked steady and breathing was estimated at 15 per minute or slower.
Important limits
This is an experimental heuristic built from a few camera-derived inputs. It is not a validated physiological measure, it is not emotion detection, and it is not a medical test. Treat it as a rough hint about the direction your signal is moving, not as a verdict about how you feel. If you feel anxious or unwell, trust that feeling over this number and seek appropriate help. A low score does not mean you are fine, and a high score does not mean something is wrong.
What actually helps
Longer exhales
Breathing in for about 4 seconds and out for about 6 is a simple way to slow down when you feel keyed up.
Re-measure calmly
Sit, rest your arm on a table, keep your finger still, and measure again after a minute. Many high readings are signal noise.
Physiological sigh
Two short inhales through the nose followed by a long exhale is another quick, low-effort way to settle.
The ONDA app is a separate product: it focuses on pulse, breathing and, with an Apple Watch, coherence. It does not use the formulas on this page.
The ONDA Principle
Alarm reacts to an irregular-looking rhythm and faster breathing. Check the signal and your surroundings before reading anything into it.
Ready to measure?
The ONDA app works with your iPhone camera, Apple Watch and Apple Health.