Summary
Systematic review found inconsistent effects of caffeine on HRV, with some studies showing decreased vagal tone and others showing no effect. Habitual consumption and individual tolerance appear to modulate response.
Methods
Systematic review of caffeine and HRV studies
Key Findings
- Acute caffeine may decrease HRV in non-habitual users
- Habitual consumers show blunted or no HRV response
- Individual variation is substantial
- Effects may depend on dose, timing, and baseline state
Limitations
Heterogeneous study designs and caffeine doses
What This Means for You
Your morning coffee probably won't tank your HRV if you're a regular drinker. But if you're measuring HRV for accuracy, consider taking readings before caffeine consumption for consistency.
Source
Read the original paper in Journal of Caffeine Research ↗
Added to HRV Zone: 2025-01-07