Vitals Knowledge Vault

HRV signatures (alcohol)

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HRV signatures (alcohol)

Key principle

Alcohol produces dose-dependent HRV suppression — both acutely and the next morning. This is the primary wearable biometric signal for alcohol detection.

Acute effects (during consumption)

Low dose (~1 standard drink)

  • RMSSD reduced (measurable); HR and LF/HF not significantly altered

Moderate dose (~2 drinks)

  • RMSSD significantly decreased
  • HR elevated
  • LF/HF ratio significantly increased (sympathetic shift)

Dose-response threshold (PMC5878366): 2 drinks is the threshold for significant RMSSD decrease + HR increase + LF/HF shift. 1 drink = RMSSD altered but NOT HR or LF/HF.

Higher doses

  • Effects extend 4–6+ hours post-consumption
  • RMSSD suppressed in both men (hours 1–5) and women (hours 2–4)

Next-morning effects (hangover phase)

  • RMSSD ↓ 30–50% of baseline — most consistent finding
  • Resting HR elevated +10–25 bpm above baseline (dose-dependent)
  • LF/HF ratio remains elevated — sustained sympathetic tone
  • pNN50 suppressed next morning (PMC10312973)
  • Recovery timeline: ~24 h for moderate session; 48–72 h after heavy session for full HRV normalisation

Mechanism

Three overlapping drivers:

  1. GABA-A potentiation → direct autonomic effects during intoxication
  2. Glutamate NMDA rebound → autonomic hyperexcitability during hangover phase
  3. CYP2E1/ROS/NF-κB → systemic inflammation → elevated sympathetic tone

Mechanism

Two overlapping drivers:

  1. GABA-A potentiation → direct autonomic effects during intoxication
  2. Glutamate NMDA rebound → autonomic hyperexcitability during hangover phase
  3. CYP2E1/ROS/NF-κB → systemic inflammation → elevated sympathetic tone

Dose-response

Strong, consistent dose-response relationship confirmed across multiple studies:

  • 1 drink: measurable RMSSD reduction, minimal HR change
  • 2 drinks: significant RMSSD + HR + LF/HF effects
  • 3+ drinks: effects worsen; HRV suppression extends well into next day

Wearable accuracy

  • Oura Gen 4: MAPE=5.96% for HRV measurement
  • WHOOP: MAPE=8.17%
  • No wearable can specifically attribute HRV suppression to alcohol vs. other stressors without motion and sleep context

Vitals implication

HRV suppression combined with elevated RHR is the best candidate signal for alcohol events. Context features (motion, sleep architecture) help distinguish from illness or training stress.

Alcohol, Sleep architecture (alcohol), Alcohol detection model

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