Central Sleep Apnea: Causes, Symptoms & Treatment

What Is Central Sleep Apnea? The Brain Signaling Failure Explained

Central sleep apnea is defined by the complete cessation of breathing effort — the diaphragm and chest wall stop moving — because the brainstem temporarily fails to issue the motor commands that drive respiration. This is the fundamental difference between central and obstructive sleep apnea: in obstructive sleep apnea (OSA), the brain continues sending signals and the respiratory muscles keep trying, but airflow stops because the upper airway collapses. In CSA, the drive to breathe itself disappears.

The neural architecture responsible for breathing originates in the pre-Bötzinger complex in the medulla and is modulated by chemoreceptors that respond to arterial carbon dioxide (CO2) and oxygen (O2). Under normal physiology, rising CO2 triggers a respiratory drive that prevents apnea. In CSA, one of several disruptions can break this loop: the central chemoreceptor threshold may sit too close to the resting CO2 level (a narrow CO2 reserve), cardiac output may delay the feedback signal between the lungs and chemoreceptors (as in heart failure), brainstem pathways may be suppressed by opioids, or hypoxia at altitude may cause a ventilatory overshoot that drives CO2 below the apnea threshold.

The clinical consequence is an apnea with no associated respiratory effort — confirmed on polysomnography by the absence of thoracic and abdominal movement belts activity during the breathing pause. This effortless apnea is what separates CSA from OSA on the sleep study tracing, and it is why interventions that simply splint the airway open (like standard CPAP) do not address the root problem.

Types of Central Sleep Apnea: Five Distinct Subtypes

Central sleep apnea is not a single diagnosis but a family of subtypes that share the same polysomnographic feature — absent respiratory effort during apnea — but have different underlying mechanisms, prognoses, and treatment approaches.

• Primary (idiopathic) CSA: No identifiable cause. The CO2 reserve is narrowed and the chemoreceptor loop becomes unstable during sleep onset and light NREM sleep. This subtype is rare and tends to affect middle-aged men. Treatment focuses on stabilizing ventilatory control, typically with low-level CPAP or acetazolamide in some cases.
• Cheyne-Stokes respiration (CSR-CSA): The most clinically significant subtype. A cyclic pattern of crescendo-decrescendo breathing separated by central apneas, driven by the prolonged circulatory delay between the lungs and chemoreceptors in patients with reduced cardiac output. The 2015 SERVE-HF trial (Cowie et al., New England Journal of Medicine) enrolled 1,325 patients with systolic heart failure (EF ≤45%) and symptomatic CSR-CSA. ASV was found to significantly suppress central apneas but unexpectedly increased all-cause mortality (hazard ratio 1.28) and cardiovascular mortality (HR 1.34) compared to guideline-based medical therapy alone. This landmark finding reversed prior assumptions and now means ASV is contraindicated in patients with symptomatic heart failure and reduced ejection fraction (HFrEF) who have predominantly CSR-CSA. Cheyne-Stokes in patients with preserved ejection fraction (HFpEF) or stroke remains a different clinical question.
• Treatment-emergent CSA (complex sleep apnea): Central apneas that appear or persist after OSA is treated with CPAP. Discussed in detail in the section below.
• Opioid-induced CSA: Chronic opioid use — particularly long-acting formulations and methadone — suppresses central chemoreceptor sensitivity and can cause both central apneas and an ataxic breathing pattern (Biot's respiration). A 2014 study by Correa et al. in Sleep Medicine found central apneas in 30% of patients on chronic opioid therapy undergoing polysomnography, with severity correlating with total daily morphine equivalents. Dose reduction is the most effective intervention when clinically feasible; ASV has supporting data in this population.
• High-altitude CSA: Ascent above ~2,500 meters triggers periodic breathing driven by hypoxic hyperventilation that overshoots and drives CO2 below the apnea threshold. Acclimatization resolves the pattern within days to weeks for most individuals; acetazolamide (a carbonic anhydrase inhibitor that maintains mild metabolic acidosis and thereby sustains ventilatory drive) is the evidence-based pharmacological option for prevention and treatment.

How Central Sleep Apnea Is Diagnosed (and Why It Differs from OSA on Sleep Study)

Diagnosing central sleep apnea requires an in-laboratory polysomnogram (PSG) — or, in selected cases, an attended cardiorespiratory study — that directly measures respiratory effort, a parameter most home sleep apnea tests (HSATs) do not reliably capture.

The AASM scoring criteria (Berry et al., Journal of Clinical Sleep Medicine, 2012 and 2017 updates) define a central apnea as a cessation of oronasal airflow for at least 10 seconds with no associated thoracoabdominal respiratory effort, as measured by inductance plethysmography or piezoelectric effort belts. A diagnosis of CSA requires a central apnea index (CAI) of at least 5 per hour, with central apneas comprising more than 50% of total respiratory events.

Because most commercially available home sleep tests use peripheral arterial tonometry or nasal pressure alone, they cannot distinguish central from obstructive events. A patient with suspected CSA, significant cardiac or neurological comorbidity, or an HSAT showing elevated AHI without the expected clinical picture of OSA should be referred for full PSG with esophageal or effort belt respiratory monitoring.

Key parameters that distinguish CSA on the PSG tracing include:

• Absence of respiratory effort: Flat thoracic and abdominal inductance channels during apnea, in contrast to the increasing paradoxical effort seen in obstructive events.
• Crescendo-decrescendo waxing-waning tidal volume: The hallmark of Cheyne-Stokes respiration, visible on the flow channel.
• Timing relative to sleep stage: CSA events cluster in NREM stage 1 and 2, when CO2 reserve is narrowest and the loop gain of the ventilatory control system is highest.
• Associated cardiac data: Because CSR-CSA is so strongly linked to heart failure, the clinical context — echocardiographic ejection fraction, BNP/NT-proBNP, prior cardiovascular history — is essential to the diagnostic interpretation and treatment decision.

If cardiac-origin CSA is suspected, referral to both a sleep specialist and a cardiologist is standard of care. The sleep study finding alone does not determine treatment — the underlying cardiac function does.

Central Sleep Apnea Treatment: ASV, BiPAP, Oxygen, and Addressing the Cause

Treatment for central sleep apnea is driven by the underlying subtype, and no single therapy is appropriate across all forms of CSA — a critical difference from OSA, where CPAP is the universal first-line recommendation.

Adaptive Servo-Ventilation (ASV)

ASV is a sophisticated pressure-support mode that continuously adjusts inspiratory pressure support and backup respiratory rate in real time to stabilize ventilation and prevent both apneas and hyperpneas. It is the most effective technology for suppressing central apneas in patients without significant systolic heart failure. A 2006 study by Teschler et al. in CHEST demonstrated that ASV achieved an AHI below 5 in 100% of patients with CSR-CSA secondary to heart failure (in that earlier, smaller cohort), but the SERVE-HF mortality data now overrides efficacy data for the HFrEF population. ASV is contraindicated per AASM guidelines in patients with symptomatic heart failure and EF ≤45% with predominantly central/CSR apneas. For other CSA subtypes — treatment-emergent CSA, opioid-induced CSA, and idiopathic CSA — ASV remains an effective option.

BiPAP with a Backup Rate (BiPAP-ST or BiPAP-ASV)

Bilevel positive airway pressure with a spontaneous-timed backup rate guarantees a minimum number of breaths per minute, which prevents prolonged central apneas. It is appropriate for patients who cannot tolerate ASV or whose CSA has a simpler periodic breathing pattern.

Supplemental Oxygen

For high-altitude CSA, supplemental oxygen raises alveolar PO2, blunts hypoxic ventilatory overshoot, and can terminate periodic breathing. In cardiac CSA where ASV is contraindicated (HFrEF), nocturnal supplemental oxygen has shown modest reductions in AHI and some improvement in exercise tolerance, though without the mortality benefit of optimal heart failure medical therapy. Oxygen therapy is generally considered adjunctive rather than definitive for most CSA subtypes.

Treating the Underlying Cause

For the majority of CSA subtypes, addressing the root driver is the most durable intervention: optimizing guideline-directed medical therapy (GDMT) for heart failure, reducing or tapering opioids under supervised care for opioid-induced CSA, acclimatization or acetazolamide for high-altitude CSA, and managing brainstem pathology for neurological CSA. A 2020 review in Sleep Medicine Reviews (Naughton et al.) noted that improvement in cardiac function — particularly left ventricular ejection fraction — is accompanied by parallel reduction in Cheyne-Stokes severity, reinforcing that CSA in heart failure is a marker of hemodynamic instability, not a separate disease.

Treatment-Emergent Central Sleep Apnea: When CPAP Causes CSA

Treatment-emergent central sleep apnea (also called complex sleep apnea syndrome) is a phenomenon in which central apneas that were absent or below diagnostic threshold before treatment appear or become dominant after CPAP is initiated for obstructive sleep apnea — a clinically important scenario that affects an estimated 5–15% of patients starting CPAP therapy.

The mechanism is not fully established, but the prevailing explanation is that CPAP eliminates the arousal-triggering obstructive events that had been stabilizing the patient's breathing rhythm. With obstructive events suppressed, a narrowed CO2 reserve — which had been masked — becomes unmasked, causing instability in the ventilatory control loop and central apneas. In other words, the underlying vulnerability to central apnea existed before CPAP; OSA was obscuring it.

A landmark study by Morgenthaler et al. (2006, Sleep) defined complex sleep apnea syndrome and reported that among 223 consecutive patients referred for CPAP titration with confirmed OSA, 15% met criteria for treatment-emergent CSA on their titration night. Of these, most had a residual AHI driven by central events despite adequate airway pressures.

The critical clinical insight — and one that is consistently underemphasized on competitor resources — is that the majority of treatment-emergent CSA cases resolve spontaneously within 4–12 weeks of continued CPAP therapy without any intervention. The standard recommendation from the AASM is to continue CPAP and reassess with a repeat titration study at 8–12 weeks. Escalating to ASV immediately is typically not indicated unless the patient is symptomatic and the central apneas persist beyond this window or are causing significant oxygen desaturation.

For the minority of patients in whom treatment-emergent CSA persists at 3 months, ASV is the most effective option and avoids the need to abandon CPAP therapy entirely. These patients benefit from specialist evaluation to rule out the causes of true, non-emergent CSA — particularly cardiac and opioid-related etiologies — before committing to ASV.

If you are on CPAP and your device data shows a high residual AHI with central events, discuss this finding with a sleep specialist rather than discontinuing CPAP. The presence of central events on a CPAP data download does not automatically indicate treatment failure — context and trajectory matter.

Prognosis and What to Expect

The prognosis of central sleep apnea is directly tied to the underlying cause, and the range spans from benign self-resolution to significant cardiovascular mortality risk.

For idiopathic CSA, the condition is typically chronic but not independently life-threatening. Most patients manage effectively with appropriate PAP therapy, and the primary burden is the impact of fragmented sleep on energy, cognition, and heart rate variability. With effective treatment, patients commonly report improvements in daytime alertness, mood, and the kind of metabolic recovery markers — resting heart rate, HRV, morning readiness scores — that track with sleep quality restoration.

For Cheyne-Stokes CSA in heart failure, the CSA itself is a marker of hemodynamic severity. The SERVE-HF findings established that aggressively suppressing the central apneas with ASV does not improve outcomes in this group and may cause harm — suggesting that CSR in HFrEF reflects the cardiac problem rather than causing it independently. Prognosis is governed by left ventricular function and GDMT adherence, not sleep apnea treatment per se.

For opioid-induced CSA, the trajectory depends on whether opioid modification is feasible. Dose reduction, rotation to less respiratory-suppressive opioids, or medically supervised tapering can meaningfully reduce CSA severity. Where opioids are medically necessary and cannot be reduced, ASV provides a reasonable and effective treatment pathway.

For treatment-emergent CSA, the prognosis is generally favorable: the majority of cases resolve with continued CPAP therapy and do not require escalation.

Across all subtypes, the downstream metabolic consequences of untreated sleep-disordered breathing — impaired glucose regulation, elevated cortisol, suppressed testosterone, worsened brain fog, and cardiovascular strain — are targets that respond to effective treatment. Our metabolic assessment can help identify how sleep disruption may be affecting your hormonal and metabolic biomarkers, and our hormone testing panel captures the downstream effects of poor sleep quality on cortisol, testosterone, and insulin sensitivity.