Sleep Apnea Misdiagnosis: Why Millions Are Living with the Wrong Diagnosis

Imagine being told you have depression, prescribed antidepressants, and spending years wondering why you still feel exhausted every morning. Now imagine discovering that the real cause was never a chemical imbalance in your brain — it was a physical obstruction in your airway that stopped your breathing dozens of times every night. For millions of people around the world, this is not a hypothetical scenario. It is their lived reality.

Sleep apnea is one of the most common yet most frequently misdiagnosed medical conditions on the planet. According to the American Academy of Sleep Medicine, approximately 30 million Americans have obstructive sleep apnea (OSA), but only about 6 million have ever been diagnosed. That means nearly 24 million people in the United States alone are living with a condition that silently damages their heart, brain, metabolism, and quality of life — without ever knowing it. Globally, an estimated 936 million people have some form of OSA, making it more common than asthma or diabetes.

The consequences of this diagnostic failure are not abstract. A 2026 study published in Thorax estimated that untreated sleep apnea costs the US economy up to $180.2 billion per year in lost workplace productivity alone. But the human cost is even greater: untreated OSA is associated with a threefold increase in the risk of death, with approximately 42 percent of related deaths attributed to cardiovascular disease or stroke, according to AASM data. If you suspect your fatigue, mood changes, or cardiovascular problems might be connected to a sleep disorder, understanding how and why sleep apnea gets missed could be the most important health decision you make this year.

What Is Sleep Apnea? Understanding the Three Types

Sleep apnea is a chronic condition in which a person’s breathing repeatedly stops and starts during sleep. These breathing interruptions, called apneas, can last from 10 seconds to more than a minute and may occur dozens or even hundreds of times per night. The result is fragmented sleep, oxygen deprivation, and a cascade of downstream health consequences that affect nearly every organ system in the body.

There are three distinct types of sleep apnea, each with a different underlying mechanism, and confusing one for another is itself a form of misdiagnosis.

Understanding which type of sleep apnea you have is critical because each requires a different treatment approach. A patient with central sleep apnea placed on standard CPAP therapy may see no improvement or even worsening of symptoms. This is one reason why a second opinion from a board-certified sleep medicine specialist can be invaluable — the wrong diagnosis leads to the wrong treatment, and the wrong treatment leads to patients abandoning therapy and continuing to suffer. If you have been told you need a second opinion before undergoing any medical procedure, our guide on when and how to seek one is a good starting point.

The Scale of the Crisis: How Many People Are Living with the Wrong Diagnosis?

The global misdiagnosis and underdiagnosis of sleep apnea represents one of the largest gaps between disease prevalence and diagnosis in modern medicine. Between 80 and 90 percent of people with moderate to severe obstructive sleep apnea have never been diagnosed, according to a systematic review published in Sleep Medicine Reviews. In practical terms, this means that for every person currently using a CPAP machine or oral appliance, there are four to nine others who have the same condition but have no idea.

In the United States, the numbers are staggering. The American Academy of Sleep Medicine estimates that approximately 30 million Americans have OSA, but only about 6 million have been diagnosed. The remaining 24 million are navigating their daily lives with a condition that fragments their sleep, starves their organs of oxygen, and raises their risk of heart attack, stroke, type 2 diabetes, and motor vehicle accidents.

A 2025 study published in Respiratory Medicine by researchers analyzing US population data found that the true prevalence of OSA may be even higher than previously estimated, affecting approximately 23 percent of the adult population. Among adults over 65, the prevalence of at least mild OSA approaches 50 percent, with about 20 percent having moderate to severe disease.

The economic toll of this diagnostic failure is enormous. A 2026 study by Rehman et al., published in the BMJ journal Thorax, calculated that untreated sleep apnea costs the US economy up to $180.2 billion annually in lost workplace productivity. That works out to approximately $3,727 per affected worker per year — more than double the estimated $1,661 annual cost of CPAP treatment for moderate to severe cases. In the United Kingdom, the same study estimated annual productivity losses of £4.22 billion, or 0.2 percent of national GDP. The researchers concluded that every dollar spent on early diagnosis and treatment would yield a net economic benefit.

Why Sleep Apnea Gets Misdiagnosed: The Conditions It Mimics

Sleep apnea is frequently misdiagnosed because its symptoms overlap with many other common conditions. Rather than being recognized as a breathing disorder, the downstream effects of fragmented sleep and chronic oxygen deprivation are often treated as standalone diagnoses. Patients may spend years cycling through medications for conditions they do not actually have before anyone thinks to evaluate their sleep.

The most common misdiagnoses include the following conditions.

Depression and anxiety. Chronic sleep deprivation caused by untreated OSA produces symptoms that are virtually indistinguishable from major depressive disorder: persistent fatigue, difficulty concentrating, irritability, low motivation, and changes in appetite. A study referenced by the CDC found a significant link between depression diagnoses and undiagnosed sleep apnea. Researchers at the American Academy of Sleep Medicine have noted that many patients prescribed antidepressants or anti-anxiety medications see no improvement because the root cause — disrupted breathing during sleep — remains untreated. If your doctor has attributed your symptoms to anxiety but something still feels off, our article on conditions commonly misdiagnosed as anxiety explores this issue in depth.

Insomnia. Paradoxically, many sleep apnea patients report difficulty falling asleep or staying asleep rather than the expected excessive daytime sleepiness. This is especially true in women, who are more likely to present with insomnia-type symptoms. When a clinician hears “I can’t sleep,” the instinct is often to prescribe a sleep aid rather than to investigate whether a breathing disorder is causing the repeated awakenings.

Hypothyroidism. The fatigue, weight gain, brain fog, and cold sensitivity associated with hypothyroidism overlap significantly with the symptoms of OSA. While the two conditions can coexist, patients whose thyroid levels are normal or borderline may receive a thyroid diagnosis and treatment that fails to address the underlying sleep disorder.

Chronic fatigue syndrome (CFS/ME). Patients with unexplained, persistent fatigue that does not improve with rest may receive a diagnosis of chronic fatigue syndrome without ever undergoing a sleep study. Given that up to 58 percent of OSA patients report excessive daytime sleepiness at the time of diagnosis, the overlap is substantial.

Resistant hypertension. Approximately 89 percent of young adults with unexplained hypertension have been found to have OSA. When blood pressure medications fail to bring readings under control, the underlying sleep apnea may be the reason — but physicians may adjust or add medications multiple times before considering a sleep evaluation.

Attention-deficit/hyperactivity disorder (ADHD) in children. Perhaps the most consequential misdiagnosis occurs in children. Sleep-disordered breathing in children produces hyperactivity, impulsivity, difficulty concentrating, and behavioral problems that closely mimic ADHD. Up to 15 percent of children have some form of sleep apnea, yet 90 percent go undiagnosed, according to research cited by CHADD (Children and Adults with Attention-Deficit/Hyperactivity Disorder). These children may be placed on stimulant medications when what they actually need is treatment for their breathing disorder. We cover the broader issue of childhood diagnostic errors in our guide to pediatric misdiagnosis.

The Gender Gap: Why Women’s Sleep Apnea Is Systematically Overlooked

Women with obstructive sleep apnea face longer diagnostic delays and higher rates of misdiagnosis than men. An estimated 93 percent of women with moderate to severe OSA have never received a clinical diagnosis, compared with 82 percent of men, according to data from the Society for Women’s Health Research. A survey by the Alliance of Sleep Apnea Partners found that 46 percent of female patients waited more than five years before being correctly diagnosed with sleep apnea.

The reasons for this disparity are both clinical and cultural. The “typical” sleep apnea patient in medical textbooks and screening tools is an overweight, middle-aged man who snores loudly and stops breathing visibly during sleep. These screening instruments — including the widely used STOP-Bang questionnaire and the Epworth Sleepiness Scale — were validated predominantly in male populations, according to a 2025 editorial in Sleep by BaHammam. Women who do not fit this stereotype are routinely screened out.

The clinical reality is that women with OSA present differently. According to research published in BioMed Research International by Wimms et al., as many as 40 percent of women with moderate to severe OSA do not present with the “classic” symptoms of loud snoring, witnessed apneas, and excessive daytime sleepiness. Instead, women more commonly report fatigue, insomnia, morning headaches, mood disturbances, nocturia (frequent nighttime urination), and nocturnal heartburn — symptoms that are easily attributed to menopause, hormonal changes, depression, or stress.

The consequences of this diagnostic gap are measurable. A 2025 Danish nationwide cohort study by Jennum et al., published in Sleep, found that women with OSA had significantly higher mortality than female controls (hazard ratio 1.28), while the mortality difference in men was negligible (hazard ratio 1.03). Women with OSA also incurred substantially higher healthcare costs both before and after diagnosis: €8,259 per year more than controls before diagnosis and €13,730 per year more after diagnosis, compared with €4,217 and €8,749 for men. These numbers reflect the prolonged diagnostic odyssey women endure and the accumulation of comorbidities during years of untreated disease.

The gap narrows after menopause, when declining levels of progesterone and estrogen — hormones that appear to protect the upper airway — bring women’s OSA risk in line with men’s. But by that point, many women have already spent years or decades being treated for conditions they may never have had.

How a Single-Night Sleep Study Can Get It Wrong

Even when a patient is referred for a sleep study, the diagnostic process itself can produce inaccurate results. A landmark 2021 study by Lechat et al., published in the American Journal of Respiratory and Critical Care Medicine, analyzed over 11.6 million nights of sleep data from 67,278 participants and found that a single-night sleep study can misclassify 20 to 50 percent of patients due to natural night-to-night variability in breathing patterns.

The standard measure of sleep apnea severity is the Apnea-Hypopnea Index (AHI), which counts the number of breathing interruptions per hour of sleep. A single night’s AHI can vary significantly based on factors like sleep position, alcohol consumption, nasal congestion, stress, and the “first-night effect” — the difficulty many people experience sleeping normally in an unfamiliar lab environment.

The Lechat study found that among patients whose true severity was mild to moderate, approximately 50 percent were misclassified based on a single night of testing. For patients near the diagnostic threshold of 15 events per hour (the cutoff between mild and moderate OSA), the misdiagnosis probability reached 50 to 60 percent. Only patients with severe OSA (AHI above 35) were reliably classified from a single night, with accuracy around 77 percent.

The study found that diagnostic accuracy improved substantially with multinight monitoring: the F1 diagnostic score increased from 0.77 for a single night to 0.94 for 14 nights. The researchers concluded that their findings “directly challenge the use of AHI cutoffs from single-night assessments to diagnose and manage OSA.”

Home sleep apnea tests (HSATs), which are increasingly used as a more convenient and less expensive alternative to in-lab polysomnography, carry their own limitations. While HSATs can effectively identify moderate to severe OSA in patients with a high pre-test probability, they tend to underestimate the AHI because they measure total recording time rather than actual sleep time. They also cannot detect central sleep apnea, arousals, or other sleep disorders that may coexist with or mimic OSA. The American Academy of Sleep Medicine recommends that a negative or inconclusive HSAT should always be followed by an in-lab polysomnography, but in practice, many patients are simply told they “don’t have sleep apnea” and sent on their way.

The Health Consequences of Living with Undiagnosed Sleep Apnea

Untreated sleep apnea is not merely an inconvenience or a quality-of-life issue. It is an independent risk factor for some of the leading causes of death and disability in the developed world. The repeated cycles of oxygen deprivation and re-oxygenation that occur with every apneic episode trigger a systemic inflammatory response, activate the sympathetic nervous system, and place chronic stress on the cardiovascular system.

Cardiovascular disease. People with untreated moderate to severe OSA are approximately three times more likely to die from any cause than those without the condition, according to AASM data. Approximately 42 percent of OSA-related deaths are attributed to cardiovascular disease or stroke. Research has consistently shown that untreated OSA increases the risk of hypertension, coronary artery disease, atrial fibrillation, heart failure, and stroke. Up to 74 percent of people with atrial fibrillation and approximately 40 percent of people with congestive heart failure also have sleep apnea. If you have been diagnosed with a heart condition, our guide to getting a second opinion for heart disease discusses how unrecognized sleep disorders can complicate cardiac care.

Type 2 diabetes and metabolic syndrome. Up to 83 percent of patients with type 2 diabetes have some form of sleep-disordered breathing. The intermittent hypoxia caused by OSA impairs glucose metabolism, increases insulin resistance, and promotes weight gain — creating a vicious cycle in which obesity worsens OSA, and OSA worsens metabolic health.

Cognitive decline and dementia. Chronic sleep fragmentation and repeated oxygen desaturation are associated with accelerated cognitive decline, particularly affecting memory, attention, and executive function. Growing evidence links untreated OSA to an increased risk of Alzheimer’s disease and other forms of dementia.

Motor vehicle accidents. Drowsy driving caused by untreated sleep apnea is responsible for a significant proportion of road traffic accidents. Research published in the New England Journal of Medicine found that drivers with untreated OSA are at two to three times greater risk of motor vehicle crashes. The AASM has estimated that treating affected commercial drivers could prevent approximately 980 deaths annually in the United States.

Mental health. Nearly 47 percent of people with OSA report having a mental health condition. The chronic fatigue, irritability, and cognitive impairment caused by fragmented sleep contribute to depression, anxiety, and relationship difficulties. These mental health effects are often treated in isolation without recognizing their connection to an underlying breathing disorder. Our comprehensive guide to mental health misdiagnosis explores how physical conditions like sleep apnea can masquerade as psychiatric disorders.

When and How to Seek a Second Opinion for Sleep Apnea

A second opinion from a board-certified sleep medicine specialist is warranted whenever you feel that your symptoms have not been adequately explained or addressed. Getting a second opinion is a standard part of good medical care, not a sign of distrust toward your doctor.

You should consider seeking a second opinion for sleep apnea if any of the following apply to you:

Your fatigue persists despite treatment. If you have been prescribed medication for depression, anxiety, thyroid issues, or chronic fatigue but still feel persistently tired, a sleep evaluation should be on the table. Persistent fatigue that does not respond to treatment is one of the hallmark warning signs of a possible misdiagnosis.

You were told your sleep study was normal, but you still have symptoms. Given that single-night studies can misclassify up to 50 percent of mild-to-moderate cases, a “normal” result does not rule out sleep apnea. Consider requesting a multinight assessment, an in-lab polysomnography (if your initial test was a home study), or evaluation by a different sleep specialist.

You are a woman and your symptoms are atypical. If you experience insomnia, morning headaches, fatigue, mood changes, or nocturia and have been told these are related to menopause, stress, or depression without a sleep evaluation, ask for one specifically. Make sure your clinician is aware that women with OSA frequently present differently than men.

You have been diagnosed with CPAP-resistant sleep apnea. If CPAP therapy has not improved your symptoms, it is possible that you have central or complex sleep apnea rather than purely obstructive disease, or that your pressure settings need adjustment. A sleep medicine specialist can perform additional testing to differentiate between types and optimize your treatment.

Your child has been diagnosed with ADHD but also snores or breathes loudly during sleep. Before starting or continuing stimulant medication, request a pediatric sleep evaluation. Treating the underlying sleep-disordered breathing may resolve behavioral and attention problems without medication.

How to Prepare for a Sleep Apnea Second Opinion

When seeking a second opinion for a potential sleep apnea diagnosis, preparation can make the process more effective. Gather the following before your appointment: previous sleep study reports (including the raw data, not just the summary), a list of all current medications, a sleep diary covering at least two weeks (including bedtimes, wake times, and subjective sleep quality), any relevant blood work (thyroid function, metabolic panel), and input from a bed partner about your snoring patterns, breathing pauses, or restless sleep. You should also learn how to request your complete medical records to bring to your consultation.

Look for a specialist who is board-certified in sleep medicine by the American Board of Medical Specialties (ABMS) or an equivalent body in your country. Consider seeking a clinician affiliated with an accredited sleep center, as these facilities meet rigorous standards for equipment, staffing, and clinical protocols. Telemedicine has made it easier than ever to access sleep medicine specialists regardless of your geographic location — our guide to telemedicine platforms for second opinions can help you find a provider.

Emerging Diagnostic Tools and Treatment Advances

Advances in diagnostic technology are beginning to address some of the limitations that contribute to sleep apnea misdiagnosis. Wearable devices and under-mattress sensors now enable multinight home monitoring, providing clinicians with a more comprehensive picture of a patient’s breathing patterns than a single overnight test can offer. While these consumer-grade devices are not yet a replacement for clinical sleep studies, they can serve as valuable screening tools that prompt further evaluation.

On the treatment front, several developments beyond traditional CPAP therapy are expanding options for patients. Hypoglossal nerve stimulation (such as the Inspire device) offers a surgical alternative for patients who cannot tolerate CPAP, by electrically stimulating the nerve that controls tongue movement to keep the airway open during sleep. Mandibular advancement devices (MADs), custom-fitted by dental sleep medicine specialists, provide another option for mild to moderate OSA.

Perhaps most intriguingly, GLP-1 receptor agonists — medications originally developed for type 2 diabetes and weight management, such as semaglutide and tirzepatide — have shown promising results in reducing sleep apnea severity in patients with obesity-related OSA. By promoting significant weight loss, these medications can reduce the soft tissue mass that contributes to airway obstruction. Clinical trials are ongoing, and sleep medicine experts are increasingly considering these medications as part of a comprehensive treatment strategy.

Artificial intelligence is also entering the diagnostic pipeline, with algorithms being developed to analyze overnight oximetry data, audio recordings of breathing patterns, and even smartphone-captured snoring data to flag potential sleep apnea cases for further evaluation. While these tools are still in their early stages, they hold the potential to dramatically reduce the number of undiagnosed cases by lowering the barrier to initial screening.

Frequently Asked Questions About Sleep Apnea Misdiagnosis

Taking Control of Your Sleep Health

Sleep apnea misdiagnosis is not just a statistical curiosity — it is a public health crisis that affects millions of people across the United States, United Kingdom, Australia, and around the world. The condition’s ability to masquerade as depression, anxiety, insomnia, and a host of other diagnoses means that patients may spend years receiving treatment for conditions they do not have while the true cause of their suffering goes unaddressed.

If you recognize yourself in any of the scenarios described in this article — if your fatigue has not responded to treatment, if your sleep study results seem inconsistent with your experience, or if you have risk factors that have never been evaluated — you have every right to ask questions and seek a second opinion. The gap between how many people have sleep apnea and how many know they have it is one of the largest diagnostic failures in modern medicine. Closing that gap starts with awareness, and it starts with you.

This article is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for medical concerns. If you believe you may have sleep apnea, speak with your primary care physician about a referral to a board-certified sleep medicine specialist.