Long-term CPAP use is linked to substantially lower mortality, reduced cardiovascular risk, better blood sugar control, preserved cognitive function, and improved mood. A 2025 systematic review and meta-analysis found that people using positive airway pressure therapy had a 37% lower risk of dying from any cause and a 55% lower risk of dying from cardiovascular disease compared to those who went untreated. But CPAP also comes with side effects that accumulate over months and years, from nasal irritation to subtle dental shifts, and roughly a third of users struggle to stick with it. The full picture of what years on a CPAP machine does to your body is more layered than any single headline captures.
The Mortality Picture
The strongest evidence for long-term CPAP use concerns survival. A large meta-analysis published in The Lancet Respiratory Medicine in 2025 pooled data from multiple studies and found that people on positive airway pressure therapy had significantly lower all-cause mortality (about 37% lower risk) and cardiovascular mortality (about 55% lower risk) compared to untreated patients, with the benefit growing the more consistently people used the device.1The Lancet Respiratory Medicine. Effect of positive airway pressure on mortality in obstructive sleep apnoea: a systematic review and meta-analysis That finding aligns with a large French database study of over 176,000 matched patients, which found that people who stopped CPAP therapy had a roughly 39% higher risk of death over three years than those who continued.2PubMed Central. Relationship Between CPAP Termination and All-Cause Mortality: A French Nationwide Database Analysis
A 2024 study of older adults on Medicare echoed these findings, showing that those who initiated positive airway pressure therapy had roughly half the mortality risk of those who did not, and that higher utilization was progressively linked to lower death rates and fewer major cardiovascular events.3JAMA Network Open. Positive Airway Pressure, Mortality, and Cardiovascular Risk in Older Adults With Sleep Apnea The dose-response pattern is important: people who used the device more had better outcomes, which strengthens the case that CPAP itself is driving the benefit rather than some unmeasured difference between people who happen to use it and those who don’t.
Heart Health and Blood Pressure
Untreated obstructive sleep apnea hammers the cardiovascular system night after night. Each time your airway collapses, oxygen drops, stress hormones surge, and blood pressure spikes. Over years, that cycle damages blood vessels and strains the heart. Long-term CPAP use interrupts this pattern, and the cardiovascular payoff is measurable. Two independent studies tracking patients for a decade found that cardiovascular disease and death from heart attacks and strokes increased only among those who went untreated.4PubMed Central. Cardiovascular disease risk reduction with sleep apnea treatment
Blood pressure is the most closely studied cardiovascular marker. Meta-analyses show CPAP lowers blood pressure by an average of about 2 mmHg, with bigger drops in people who have more severe apnea or who use the device more faithfully.4PubMed Central. Cardiovascular disease risk reduction with sleep apnea treatment That sounds small, but at a population level, even a 2 mmHg drop in blood pressure meaningfully reduces the risk of stroke and heart disease. A study tracking patients over two years found that those with good adherence (averaging more than four hours a night on most nights) showed a steady decline in diastolic blood pressure of about 0.13 mmHg per month, even without losing weight.5Scientific Reports. Long-term effect of continuous positive airway pressure therapy on blood pressure in patients with obstructive sleep apnea The systolic pressure trend moved in the same direction but didn’t reach statistical significance in that particular study, which highlights that the blood pressure benefits of CPAP are real but modest and somewhat inconsistent across different measures.
Atrial Fibrillation and Heart Rhythm
Sleep apnea and atrial fibrillation are closely intertwined. Repeated oxygen drops and pressure swings inside the chest can trigger and perpetuate abnormal heart rhythms. For people who have already undergone catheter ablation to treat atrial fibrillation, the question of whether CPAP prevents it from coming back is clinically important and the evidence is mixed in an interesting way.
A meta-analysis of multiple studies found that CPAP use was associated with a 42% lower risk of atrial fibrillation recurrence overall, whether patients had undergone ablation or were managed with medication alone.6PubMed. Effect of Obstructive Sleep Apnea Treatment on Atrial Fibrillation Recurrence: A Meta-Analysis However, a randomized controlled trial found no difference in recurrence at all: 57% in the CPAP group, 57% in the standard-care group, and 57% in those without sleep apnea.7Heart Rhythm. Effect of continuous positive airway pressure therapy on recurrence of atrial fibrillation after pulmonary vein isolation in patients with obstructive sleep apnea: A randomized controlled trial That trial is sobering, but it measured recurrence over a relatively short window. A more recent study focused specifically on very late recurrence (beyond one year after ablation) and found that long-term CPAP adherence cut that rate dramatically, from about 22% to about 8%.8PubMed Central. Impact of Long-Term CPAP Adherence on Recurrence After Atrial Fibrillation Ablation in Patients With Severe Sleep Apnea The takeaway: CPAP probably doesn’t prevent the early electrical remodeling that leads to short-term recurrence after ablation, but it may protect against the gradual cardiac changes that cause the problem to creep back years later.
Brain Health and Cognitive Function
Sleep apnea fragments your sleep architecture and starves the brain of oxygen hundreds of times a night. Over years, that takes a toll on memory, attention, and executive function. CPAP’s ability to protect or even partially restore cognitive function is one of the more compelling long-term benefits, particularly for people already showing signs of decline.
A preliminary study of patients with both Alzheimer’s disease and obstructive sleep apnea found that those who used CPAP consistently showed less cognitive deterioration over time than those who did not, along with stabilization of depressive symptoms and improved sleep quality.9PubMed Central. Sustained Use of CPAP Slows Deterioration of Cognition, Sleep, and Mood in Patients with Alzheimer’s Disease and Obstructive Sleep Apnea: A Preliminary Study A larger retrospective study reinforced this, finding that good CPAP adherence over two to twelve months was associated with meaningfully higher scores on standard cognitive tests compared to poor adherence or no CPAP at all, even after adjusting for age, sex, body mass index, and other health conditions.10Sleep Medicine. Investigating changes in cognition associated with the use of CPAP in cognitive impairment and dementia: A retrospective study
These findings don’t prove CPAP reverses dementia. But they suggest that for people whose cognitive decline is being accelerated by untreated sleep apnea, consistent CPAP use can slow that trajectory. Given that there are few effective interventions for cognitive decline in older adults, that is not a small thing.
Blood Sugar and Metabolic Health
Obstructive sleep apnea worsens insulin resistance through a mix of intermittent oxygen deprivation, sleep fragmentation, and sympathetic nervous system activation. For people with type 2 diabetes, CPAP has the potential to improve blood sugar control, though the effect is not as dramatic as the cardiovascular benefits.
A systematic review and meta-analysis found that CPAP treatment led to a modest but statistically significant reduction in hemoglobin A1c (a measure of average blood sugar over three months) of about 0.24 percentage points compared to control groups, and the improvement was directly tied to how many hours per night patients used the device.11European Respiratory Review. Effects of continuous positive airway pressure therapy on glucose metabolism in patients with obstructive sleep apnoea and type 2 diabetes: a systematic review and meta-analysis A quarter of a percentage point may not sound like much, but for someone whose diabetes is borderline controlled, it could be the difference between needing an additional medication and not. A clinical study found that about 59% of diabetic patients showed some improvement in blood sugar after starting CPAP, though the degree of response varied widely.12PubMed Central. Obstructive sleep apnea in Type 2 diabetes and impact of continuous positive airway pressure therapy on glycemic control
Researchers have noted that the evidence on CPAP and glucose metabolism remains somewhat mixed, with how long treatment lasts and how faithfully patients use the device both playing major roles in whether the benefits materialize.13PubMed Central. Continuous positive airway pressure to improve insulin resistance and glucose homeostasis in sleep apnea There’s also the kidney angle: one trial found that among patients who actually adhered well to CPAP, there was a greater reduction in a marker of kidney stress (urine albumin), along with better blood sugar control, though in the broader group the kidney benefit did not reach significance.14PubMed Central. Continuous Positive Airway Pressure Therapy for Chronic Kidney Disease in Patients with Obstructive Sleep Apnea: The Jury Is Still Out The pattern across metabolic outcomes is consistent: CPAP helps, but the help depends heavily on the person using it enough hours each night.
Depression and Emotional Health
Untreated sleep apnea and depression frequently travel together. Chronic sleep disruption, daytime exhaustion, and the social consequences of loud snoring and restless nights all feed into low mood. CPAP addresses the sleep side of that equation, and long-term studies show measurable improvements in depressive symptoms.
One study found that after an average of about a year and a half on CPAP, patients’ depression scores dropped significantly. But the picture wasn’t uniformly rosy: about 42% of patients still had persistent depressive symptoms despite treatment.15PubMed. Depressive symptoms before and after long-term CPAP therapy in patients with sleep apnea The strongest predictor of persistent depression was continued excessive daytime sleepiness despite CPAP, suggesting that for some people the device doesn’t fully resolve the fatigue that drives their mood problems. Women and people with existing cardiovascular disease were also more likely to have lingering depressive symptoms. A separate study found that improvements in depressive symptoms and emotional regulation seen at four months were maintained at twelve months, which is encouraging for the durability of the mood benefit.16PubMed. Improved depressive symptoms, and emotional regulation and reactivity, in individuals with obstructive sleep apnea after short- and long-term CPAP therapy use
Inflammation and Blood Vessel Repair
One of the less visible but potentially most important long-term effects of CPAP is what it does to the inner lining of your blood vessels. Untreated sleep apnea causes chronic inflammation and oxidative stress that damages the endothelium, the thin layer of cells that controls how blood vessels dilate and contract. Over time, this endothelial dysfunction sets the stage for atherosclerosis.
A systematic review and meta-analysis found that CPAP significantly improved endothelial function, measured by flow-mediated dilation, by nearly 4 percentage points compared to controls, a degree the authors considered clinically important.17PubMed. Effect of CPAP therapy on endothelial function in obstructive sleep apnoea: A systematic review and meta-analysis Studies of the molecular changes tell the same story: in patients who used CPAP at least four hours nightly, markers of oxidative stress and harmful inflammation in blood vessel tissue decreased, while the protective enzyme that produces nitric oxide (the molecule that tells blood vessels to relax) increased.18PubMed Central. Inflammation, oxidative stress, and repair capacity of the vascular endothelium in obstructive sleep apnea This vascular repair is likely one of the pathways through which CPAP reduces cardiovascular events and death over time.19PubMed Central. Endothelial function in obstructive sleep apnea
Driving Safety
People with untreated obstructive sleep apnea are at significantly elevated risk of motor vehicle accidents, driven by excessive daytime sleepiness and impaired reaction time. CPAP’s effect here is one of its most clear-cut long-term benefits. A meta-analysis of nine observational studies found that CPAP use reduced crash risk by about 72% compared to pre-treatment rates.20PubMed Central. Continuous positive airway pressure reduces risk of motor vehicle crash among drivers with obstructive sleep apnea: systematic review and meta-analysis Data from the Swedish traffic accident registry showed a similar pattern: among drivers who used CPAP at least four hours per night, accident rates dropped from about 7.6 to 2.5 per thousand drivers per year.21PubMed Central. Sleep apnea-related risk of motor vehicle accidents is reduced by continuous positive airway pressure: Swedish Traffic Accident Registry data For anyone who drives for a living, this is arguably the most immediately relevant long-term effect of treatment.
Nasal Irritation and Airway Side Effects
The benefits above are real, but CPAP also comes with physical side effects that worsen or persist with prolonged use. The most common complaint is nasal trouble. Pushing pressurized air through the nose all night can cause chronic dryness, congestion, and runny nose. Biopsies of nasal tissue in long-term CPAP users have revealed chronic low-grade inflammation beneath the lining of the nose, consisting of immune cells that indicate ongoing irritation. Adding heated humidification to the CPAP setup significantly reduced both the inflammation and the buildup of scar-like tissue in the nasal lining.22European Respiratory Journal. Nasal inflammation in sleep apnoea patients using CPAP and effect of heated humidification
A study tracking nasal symptoms over three months found that high CPAP users developed worse runny nose symptoms, though other nasal complaints like stuffiness and sneezing didn’t change significantly.23PubMed Central. Nasal Symptoms in Patients with Obstructive Sleep Apnoea and Their Association with Continuous Positive Airway Pressure Usage The irony is that these nasal symptoms are one of the main reasons people stop using CPAP, which is why heated humidification and proper mask fitting aren’t just comfort measures but genuine long-term health strategies.
Dental Changes and Eye Pressure
A less well-known side effect is subtle tooth movement. Case reports describe patients noticing spaces opening between their front teeth after months of CPAP use, likely caused by the tongue thrusting forward against the teeth during sleep as a response to the airflow pressure.24PubMed Central. Tooth Movement Associated With CPAP Therapy This seems to be uncommon, but it’s worth mentioning to your dentist if you notice changes in your bite or tooth spacing after starting CPAP.
Eye pressure is another concern, particularly for people with glaucoma. A study of patients with both open-angle glaucoma and sleep apnea found that after twelve months of CPAP, intraocular pressure rose significantly from baseline. However, the visual field measurements that track actual glaucoma progression didn’t significantly worsen over that same period, leading the researchers to conclude that CPAP didn’t accelerate glaucoma but does warrant monitoring.25PubMed Central. Long-term Effect of Continuous Positive Air Pressure Therapy on Intraocular Pressure in Patients with Primary Open-angle Glaucoma with Obstructive Sleep Apnea If you have glaucoma and use CPAP, regular eye pressure checks are a good idea.
Respiratory Infections and Lung Function
A reasonable worry about breathing pressurized air through a mask every night is whether it increases your risk of respiratory infections. An adjusted analysis found no significant association between positive airway pressure use and the rate of respiratory infections.26Journal of Clinical Sleep Medicine. Respiratory infection risk in positive airway pressure therapy users: a retrospective cohort study Regular cleaning of the mask, tubing, and humidifier chamber remains good practice, but the fear that CPAP acts as a conduit for infections doesn’t appear to be supported by the data.
Lung function is a more nuanced story. After a year of CPAP, one study found that blood oxygen levels improved significantly across all patients. But what happened to airflow measures depended on where patients started. Those with reduced baseline lung function saw improvement, while those who started with normal lung function actually showed a small decline.27PubMed Central. The effect of continuous positive airway pressure on pulmonary function may depend on the basal level of forced expiratory volume in 1 second This may be relevant for people who have both sleep apnea and an obstructive lung condition like COPD, a combination sometimes called overlap syndrome. For most CPAP users without underlying lung disease, overall respiratory function appears to be unaffected or mildly improved.
The Adherence Problem
None of the benefits above matter much if the device sits on the nightstand unused. Adherence is the Achilles heel of CPAP therapy, and the numbers have barely budged over two decades. A review of adherence data spanning twenty years found that the average use hovers around four and a half hours per night, with roughly a third of patients classified as non-users.28PubMed Central. Trends in CPAP adherence over twenty years of data collection: a flattened curve A single-center study found that about 20% of patients drop off within the first ten months, with more gradual attrition over the following years, and only about half of patients still on treatment at their last recorded visit.29PubMed Central. Factors Affecting Long-Term Compliance of CPAP Treatment—A Single Centre Experience For people with mild sleep apnea specifically, long-term adherence can be even harder to maintain: one study found only about 26% remained adherent.30PubMed Central. Long term adherence to continuous positive Airway pressure in mild obstructive sleep apnea
The practical implication is that if you’re struggling with CPAP, you’re not alone and you shouldn’t assume the problem is unsolvable. Mask fit, pressure settings, humidification, and the type of interface (nasal pillows, nasal mask, or full-face mask) can all be adjusted. For people who truly can’t tolerate CPAP, oral appliances are an alternative. A two-year follow-up study comparing oral appliances with CPAP found no significant difference in the proportion of patients who had successful treatment outcomes, though CPAP was more effective at eliminating breathing events and maintaining oxygen levels.31PubMed Central. 2-Year Follow-Up of Oral Appliance Versus CPAP for OSAS
Effects on Bed Partners
Sleep apnea is not a solo disease. The person lying next to someone with untreated apnea often endures loud snoring, witnessed breathing pauses, and their own disrupted sleep. CPAP consistently improves bed-partner sleep quality across multiple studies.32PubMed Central. Impact of Obstructive Sleep Apnea and Its Treatments on Partners: A Literature Review The evidence for improvements in partner mood and relationship quality is more mixed, but one study found that good CPAP adherence in men was associated with a better intimate relationship with their bed partner, likely because reduced daytime sleepiness meant more energy and engagement.33PubMed. A pathway underlying the impact of CPAP adherence on intimate relationship with bed partner in men with obstructive sleep apnea
Healthcare Costs and the Philips Recall
Long-term CPAP use appears to reduce overall healthcare spending. A study of patients with both sleep apnea and cardiovascular disease found that those who adhered to CPAP had total care costs of about $6,825 compared to roughly $11,300 for non-adherent patients, driven mainly by fewer outpatient visits and hospitalizations.34PubMed Central. Continuous Positive Airway Pressure Adherence and Treatment Cost in Patients With Obstructive Sleep Apnea and Cardiovascular Disease A broader study of people with both sleep apnea and obesity found that treated individuals had significantly lower total healthcare costs and were 18% less likely to have an emergency department visit or hospitalization.35Obesity Pillars. Impact of treatment on healthcare resource utilization and cost of care among adults with obstructive sleep apnea and obesity
On the device safety front, the 2021 Philips Respironics recall cast a shadow over long-term CPAP use. Certain older devices used a polyurethane sound-dampening foam that could degrade over time, sending small particles and chemical irritants into the air stream. Users reported respiratory symptoms, and case reports documented airway irritation from inhaling degraded foam particles.36PubMed Central. There Was Something in the Air: A Case of Interstitial Lung Disease Associated With Continuous Positive Airway Pressure (CPAP) Foam Degradation and Inhalation Syndrome The recall affected specific Philips machines and has since been addressed, but it underscored an important point: the CPAP device itself is medical hardware that requires maintenance, periodic replacement, and attention to manufacturer updates. The long-term effects of CPAP are overwhelmingly driven by the therapy, not by the machine, but keeping your equipment in good condition and staying current on any safety notices is part of responsible long-term use.