Possible causes
- Insufficient recovery – intense training without rest lowers HRV for several days.
- Alcohol – even a small amount in the evening often markedly lowers night-time HRV.
- Short or irregular sleep – disrupts recovery of the autonomic nervous system.
- Psychological stress – long-term strain keeps the sympathetic nervous system activated.
- Illness and inflammation – HRV often drops days before an infection shows.
- Age and genetics – HRV naturally declines with age and varies greatly between people.
What to check
- Your personal trend – compare your 7–30-day average with yourself, not with other people's values.
- Resting heart rate and temperature – if they rise as HRV falls, your body may be fighting an infection.
- Blood count and ferritin – anemia and iron deficiency impair recovery.
- CRP, TSH and vitamin D – for persistently low HRV and fatigue.
What helps
- Regular sleep – consistent bed and wake times are very important for HRV.
- Sensible training load – follow hard days with easy days and rest days.
- Low-intensity endurance exercise – such as brisk walking or easy running raises HRV over time.
- Slow breathing – around 6 breaths per minute for a few minutes a day.
- Less alcohol and fewer late meals – a quick way to see improvement in your data.
When to see a doctor
See a doctor if low HRV comes with an irregular pulse, palpitations, chest pain, fainting, marked shortness of breath, or if fatigue lasts a long time. The HRV number alone is not a diagnosis, and wrist-based measurement has limited accuracy.