Camera HRV · Free assessment
Understand your body's readiness for focus, learning, recovery and performance — using nothing but your smartphone camera.
Best on a mobile phone with a rear camera & flash · educational tool, not a medical device.
Section 01 · Foundation
HRV is not how fast your heart beats. It's the tiny variation in time between each beat.
Same gap every time — often linked to stress or fatigue.
Naturally variable — a sign of a responsive nervous system.
Section 02 · Relevance
HRV reflects your autonomic nervous system — the same system that governs how well you can concentrate.
Level 1
Stress
Level 2
Attention Control
Level 3
Focus Quality
Level 4
Performance
Deep Mind Club uses HRV as a readiness signal — never as a medical diagnosis.
Section 03 · Method
Three simple steps turn your phone into a light-based pulse sensor.
Place fingertip
Rest your finger gently over the rear camera lens.
Torch on
The flash illuminates blood flow just under your skin.
Signal analysed
Tiny colour changes are turned into a pulse waveform.
Section 04 · Science
Photoplethysmography (PPG) detects tiny blood-volume changes in your fingertip on every heartbeat.
Heart
Blood flow
Fingertip
Camera
PPG signal
HRV metrics
By measuring the time between successive peaks, we can estimate HRV metrics like RMSSD, SDNN and pNN50.
Section 05 · Trust
Honest expectations. Camera HRV is great for trends and readiness — not for medical decisions.
Method reliability
Gold standard · Polar H10, clinical ECG
Very good · pulse oximeters
Good for trends · this tool
90–99%
Heart rate
Good
RMSSD trends
Useful
Stress trends
What this tool is for
Section 06 · Best practice
A few small habits make the difference between noise and signal.
Rule 1
Sit comfortably
Rest your arm on a table or your lap.
Rule 2
Stay still
Movement adds noise to the signal.
Rule 3
Breathe naturally
Don't force slow or deep breathing.
Rule 4
Avoid bright sunlight
Prefer stable indoor lighting.
Rule 5
Rear camera & flash
Front cameras usually lack a torch.
Rule 6
Measure for 60 seconds
Enough beats for stable metrics.
Section 10 · FAQ
Everything most people ask before their first reading.
Section 07 · Measure
60 seconds. Fingertip on the rear camera. Voice-guided.