HRV & Sleep

Methods

Analysis of continuous HRV data from Oura Ring users over multiple weeks

Key Findings

• 5+ nights of data needed for reliable HRV-CV estimation
• Higher HRV-CV associated with alcohol consumption
• Higher HRV-CV linked to lower physical activity levels
• Higher HRV-CV correlated with inconsistent sleep schedules

Limitations

Observational data, correlation not causation

Methods

Analysis of wearable HRV data correlated with self-reported alcohol intake

Key Findings

• 1-2 drinks suppress HRV for approximately 2 days
• 3+ drinks can affect HRV for 4-5 days
• Effect is dose-dependent and cumulative
• Sleep quality also impaired during recovery period

Limitations

Self-reported alcohol intake may be underestimated

Methods

Binary logistic regression model using pre-sleep HRV in elite athletes

Key Findings

• Pre-sleep HRV predicted chronic insomnia with 96% accuracy
• Lower pre-sleep HRV associated with insomnia diagnosis
• Simple measurement could screen for sleep disorders
• Athletes with insomnia showed distinct HRV patterns

Limitations

Elite athlete population may not generalize, single study

Methods

Cross-sectional analysis of sleep duration, exercise, and HRV relationships

Key Findings

• Sleeping 6+ hours had protective effect on HRV
• Short sleep impaired restorative processes
• Inadequate exercise + short sleep = lowest HRV
• Sleep may be more foundational than exercise for HRV

Limitations

Cross-sectional design cannot establish causation

Methods

Polysomnography study measuring HRV reliability across sleep stages

Key Findings

• High-frequency HRV reliable across N2, deep sleep, and REM
• Correlations ranged from r=0.70 to r=0.88 across stages
• Reliability maintained even during disrupted sleep
• Supports overnight HRV as valid health metric

Limitations

Lab-based study may differ from home monitoring