What HRV actually measures
HRV is the moment-to-moment variability in your heart rate. Higher HRV means a more responsive autonomic nervous system — better resilience to stress, faster recovery, lower all-cause mortality risk in long-term studies.
The resonant frequency
Each person has a breathing rate at which HRV peaks — usually 5–7 breaths per minute, often called the resonant frequency. For most adults, 5.5 breaths per minute (5-5 with a brief pause) is close enough.
The 30-day expectation
A 2017 review (Lehrer et al.) found that 10 minutes a day of resonant-frequency breathing for 4 weeks measurably raises baseline HRV in healthy adults.
How to practise
Sit upright, eyes soft, hands relaxed. Coherent 5-5 for 10 minutes. Once a day, ideally the same time. Track HRV in the morning before getting out of bed.
Log your sessions in Breathe On and explore the matching guidance at [/breathing-for/stress](/breathing-for/stress).