Can Sleep Apnea Cause Low HRV?
Sleep apnea profoundly affects HRV. Each apneic event—when breathing stops for 10 seconds or more—triggers autonomic stress responses that suppress HRV and prevent normal overnight recovery. Moderate sleep apnea involves 15-30 events per hour, while severe cases exceed 30 per hour, meaning your nervous system may be jolted hundreds of times per night.
If you have unexplained low HRV despite good sleep habits, or if your HRV doesn't improve with typical interventions, undiagnosed sleep apnea may be the culprit. An estimated 80% of moderate-to-severe cases go undiagnosed, making it one of the most common hidden causes of persistently low HRV.
How Sleep Apnea Affects HRV
During apneic events: - Oxygen saturation can drop below 90%, triggering sympathetic activation - Heart rate and blood pressure spike repeatedly throughout the night - Normal deep-sleep HRV patterns are disrupted, preventing parasympathetic recovery - The "rest and digest" system can't engage fully, so your body never reaches its lowest resting heart rate
Chronic effects: - Consistently suppressed overnight HRV, often 20-40% below age-matched norms - Elevated resting heart rate by 5-15 BPM - Reduced HRV recovery capacity after exercise or stress - Blunted response to breathing exercises and other HRV interventions
Research shows sleep apnea patients often have 20-40% lower HRV than matched controls, even during waking hours. Devices like the Oura Ring or Whoop can reveal characteristic overnight patterns—flat or erratic HRV instead of the normal gradual rise during deep sleep.
How Do You Know If Sleep Apnea Is Causing Your Low HRV?
Consider sleep apnea testing if you have: - Chronically low HRV that doesn't respond to standard interventions - Low overnight HRV despite feeling like you "slept well" - Snoring (especially with gasping or pauses reported by a partner) - Daytime fatigue despite 7-9 hours of sleep - Morning headaches or dry mouth upon waking - Elevated resting heart rate during sleep (tracked by wearables)
Risk factors: - Overweight/obesity (but thin people get it too—up to 20% of cases) - Male sex (but women get it, especially post-menopause) - Age 40+ (but younger people can have it) - Neck circumference >17" (men) or >16" (women) - Family history of sleep-disordered breathing
Getting tested: Home sleep tests are now widely available and cost $150-500 without insurance. Your doctor can also refer you for an in-lab polysomnography study. Many normal HRV ranges by age assume no sleep disorders, so treating apnea can shift your numbers significantly.
Does Treating Sleep Apnea Improve HRV?
The good news: treating sleep apnea significantly improves HRV. Most patients see measurable changes within the first 2-4 weeks of consistent treatment, with continued gains over 3-6 months.
CPAP therapy effects: - HRV typically improves within weeks of consistent use (4+ hours per night) - Studies show 15-30% RMSSD improvement after 3 months - Resting heart rate often decreases by 3-8 BPM - Sleep quality scores improve on wearables, with more time in deep sleep - Morning readiness scores on devices like Whoop often jump noticeably
Other treatments: - Oral appliances (for mild-moderate cases, AHI under 15) - Weight loss (losing 10-15% body weight can reduce or eliminate apnea) - Positional therapy (for position-dependent apnea—sleeping on your side) - Surgery (in select cases with anatomical obstruction)
Many users report their HRV "unlocks" after starting treatment—suddenly responding to breathing exercises and other interventions that previously seemed ineffective. See our guide on why HRV isn't improving if you suspect a hidden issue.
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