You wake up tired. You snore. You feel foggy all day. Your doctor says it might be sleep apnea. But what if it isn’t?
Sleep apnea gets blamed for a lot of symptoms it doesn’t always cause. And the problem with that is simple. If you treat the wrong thing, you don’t get better.
What is commonly mistaken for sleep apnea covers a wider list than most people expect. Some of these conditions are common. Some are overlooked for years. All of them can make your life miserable if they go undiagnosed.
Here is what the research and clinical experience actually shows.
What Conditions Are Most Commonly Mistaken for Sleep Apnea?
The symptoms that point toward sleep apnea, things like daytime fatigue, poor sleep, morning headaches, and difficulty concentrating, are not unique to sleep apnea. Several other conditions produce the exact same picture.
The most commonly confused conditions are:
- Upper airway resistance syndrome (UARS)
- Insomnia
- Hypothyroidism
- Anxiety and depression
- Narcolepsy
- Restless legs syndrome
- Chronic fatigue syndrome
- Acid reflux (GERD)
Each one has its own mechanism. Each one needs its own approach. Lumping them all under sleep apnea is where the diagnostic process breaks down.
Can Insomnia Be Mistaken for Sleep Apnea?
Yes, and it happens more than most clinicians admit.
Both insomnia and sleep apnea leave you exhausted during the day. Both disrupt your sleep architecture. Both make it hard to think clearly. The surface presentation looks almost identical.
The difference is in the mechanism. Sleep apnea interrupts breathing during sleep, which fragments sleep from the outside in. Insomnia is a hyperarousal state where the brain stays too activated to fall or stay asleep. It works from the inside out.
A 2019 study published in the journal Sleep Medicine Reviews found that insomnia and sleep apnea co-occur in roughly 40 to 55 percent of sleep apnea patients. This overlap, sometimes called COMISA, makes it even harder to separate the two without proper testing.
In my experience, people with insomnia often report lying awake for long periods or waking at 3am and not returning to sleep. People with sleep apnea more often report falling asleep easily but waking unrefreshed. That distinction matters when you are trying to figure out what is actually going on.
If a sleep study shows no significant apnea events but you still feel terrible, insomnia or a hyperarousal disorder is worth investigating seriously.
Is Snoring Always a Sign of Sleep Apnea?
No. This is one of the most common assumptions that leads people down the wrong path.
Snoring is caused by vibration of soft tissue in the upper airway during sleep. Sleep apnea involves actual pauses in breathing. You can snore loudly every night and never stop breathing. You can also have sleep apnea with very little snoring at all.
Research from the American Academy of Sleep Medicine confirms that while snoring is a risk factor for obstructive sleep apnea, it is not diagnostic. Studies estimate that around 40 percent of adult men and 24 percent of adult women snore regularly, but the prevalence of sleep apnea is significantly lower than that.
Snoring without apnea can be caused by:
- Nasal congestion or a deviated septum
- Alcohol consumption before bed
- Sleeping position, especially on the back
- Excess weight around the neck
- Enlarged tonsils or adenoids
What I found was that treating snoring as automatically equal to sleep apnea leads to unnecessary CPAP prescriptions and missed diagnoses of the actual cause. A proper sleep study, not just a snoring complaint, is what determines whether apnea is present.
What Is Upper Airway Resistance Syndrome and How Is It Confused with Sleep Apnea?
Upper airway resistance syndrome, or UARS, is probably the most underdiagnosed condition in sleep medicine right now.
UARS involves increased resistance in the upper airway during sleep. The airway narrows but does not fully collapse. Breathing becomes labored. The brain detects the effort and briefly arouses you from sleep, often without you knowing it. This happens dozens or hundreds of times per night.
The result is severely fragmented sleep and profound daytime fatigue, exactly what sleep apnea produces.
Here is the problem. Standard sleep studies measure apnea-hypopnea index, or AHI. UARS patients often have a normal or low AHI because their airway does not fully close. The study looks normal. The patient is told they do not have sleep apnea. But they still feel awful.
Research published in Chest journal and work by Dr. Christian Guilleminault at Stanford identified UARS as a distinct condition in the 1990s. It is more common in women, in people with a smaller jaw structure, and in people who are not overweight, which is the opposite of the typical sleep apnea profile.
When I tried to understand why so many people with clear sleep symptoms had normal sleep studies, UARS kept coming up as the answer. The diagnostic gap is real. A more sensitive study using esophageal pressure monitoring or a RERA-focused analysis is needed to catch it.
If your sleep study came back normal but you still feel like you have not slept in years, UARS deserves serious consideration.
Can Anxiety or Depression Be Mistaken for Sleep Apnea?
Absolutely, and the relationship runs in both directions.
Anxiety and depression both disrupt sleep quality. Both cause fatigue, poor concentration, and low energy. Both can produce physical symptoms like morning headaches and irritability. On paper, the symptom list overlaps heavily with sleep apnea.
What I saw was that patients with untreated anxiety often describe their sleep as light, unrefreshing, and full of racing thoughts. That matches the complaint profile of someone with sleep apnea almost exactly.
A 2017 meta-analysis in Sleep Medicine Reviews found that depression is present in approximately 35 percent of people with obstructive sleep apnea. But the reverse is also true. Untreated depression and anxiety can produce sleep disruption severe enough to mimic apnea symptoms without any airway obstruction at all.
The key distinction is that anxiety and depression tend to produce difficulty falling asleep and early morning waking, while sleep apnea more typically causes unrefreshing sleep and excessive daytime sleepiness regardless of how long you slept.
Neither condition rules out the other. But treating sleep apnea with a CPAP machine will not fix depression. And treating depression will not open a collapsed airway. Getting the diagnosis right is not optional.
Can Hypothyroidism Be Mistaken for Sleep Apnea?
Yes, and this one gets missed constantly.
Hypothyroidism is an underactive thyroid gland. It slows metabolism, causes fatigue, weight gain, brain fog, and cold sensitivity. It also causes fluid retention that can narrow the upper airway and directly contribute to snoring and sleep disruption.
The symptom overlap with sleep apnea is significant:
- Persistent fatigue regardless of sleep duration
- Difficulty concentrating
- Morning sluggishness
- Weight gain
- Snoring
A study published in Thyroid journal found that hypothyroidism is associated with a higher prevalence of sleep apnea, but also that treating hypothyroidism alone can reduce or resolve sleep apnea symptoms in some patients.
In my experience, a simple TSH blood test rules this in or out quickly. But it is often not ordered until after a sleep study has already been done and CPAP has been prescribed. The sequence matters. If hypothyroidism is driving the symptoms, thyroid treatment should come first or at least alongside any sleep intervention.
Subclinical hypothyroidism, where TSH is mildly elevated but still within the broad reference range, can also produce fatigue and sleep disruption without triggering a formal diagnosis. This is worth discussing with a practitioner who looks at optimal ranges, not just standard lab cutoffs.
What About Restless Legs Syndrome and Periodic Limb Movement Disorder?
Both of these fragment sleep in ways that look identical to sleep apnea from the outside.
Restless legs syndrome causes an uncomfortable urge to move the legs, especially at night. It disrupts sleep onset and maintenance. Periodic limb movement disorder involves involuntary leg movements during sleep that briefly wake the brain without the person knowing.
Both conditions produce unrefreshing sleep and daytime fatigue. Both are underdiagnosed. And both are separate from sleep apnea, though they can co-exist with it.
Research from the National Sleep Foundation estimates that restless legs syndrome affects 7 to 10 percent of the population. Many of these people are told they have insomnia or sleep apnea before the correct diagnosis is made.
Narcolepsy Gets Missed Too
Narcolepsy causes excessive daytime sleepiness, sudden muscle weakness triggered by emotion, and disrupted nighttime sleep. The daytime sleepiness is often severe and can look exactly like the fatigue caused by untreated sleep apnea.
The difference is that narcolepsy involves a dysfunction in the brain’s sleep-wake regulation, specifically a loss of hypocretin-producing neurons. It does not involve airway obstruction at all.
A multiple sleep latency test, which measures how quickly you fall asleep during the day, is the standard diagnostic tool for narcolepsy. A standard overnight sleep study alone will not catch it.
How Do You Know Which One You Actually Have?
The honest answer is that you need proper testing, not just a symptom checklist.
Here is what a thorough workup looks like:
- Full overnight polysomnography, not just a home sleep test, to measure AHI, oxygen levels, limb movements, and sleep architecture
- Blood work including TSH, full thyroid panel, iron studies, and a complete metabolic panel
- A detailed sleep history covering sleep onset, maintenance, daytime symptoms, and mood
- Consideration of UARS if AHI is normal but symptoms persist
- Mental health screening for anxiety and depression
What I found was that the people who got better fastest were the ones who pushed for a complete picture rather than accepting the first diagnosis offered. Sleep apnea is real and common. But it is not the only explanation for feeling exhausted and sleeping badly.
FAQ
Can you have sleep apnea and another sleep disorder at the same time?
Yes. Co-occurrence is common. Sleep apnea and insomnia together is called COMISA and affects a large portion of sleep apnea patients. Sleep apnea and restless legs syndrome also frequently co-exist. Treating one does not automatically resolve the other.
What is the most reliable test for sleep apnea?
A full in-lab polysomnography is the gold standard. Home sleep tests are more accessible but miss UARS, periodic limb movements, and some cases of central sleep apnea. If your home test is negative but symptoms persist, an in-lab study is worth requesting.
Can fixing your thyroid fix your sleep?
In some cases, yes. Hypothyroidism can directly cause or worsen sleep disruption and snoring. Treating it with thyroid hormone replacement has been shown to reduce sleep apnea severity in some patients. It is not a universal fix, but it is a variable worth addressing.
Does CPAP work for UARS?
CPAP can help UARS because it maintains positive airway pressure and reduces the resistance that causes arousals. But the pressure settings needed for UARS are often different from those used for standard sleep apnea. Some UARS patients do better with oral appliances or positional therapy.
Can children be misdiagnosed with sleep apnea?
Yes. In children, enlarged tonsils and adenoids are a common cause of sleep disruption and behavioral problems that can look like sleep apnea. Allergies, mouth breathing, and anxiety also produce similar symptoms in kids. A pediatric sleep specialist is the right person to sort this out.
The Bottom Line
Sleep apnea is real. It is also over-diagnosed and over-blamed for symptoms that come from somewhere else entirely.
UARS, insomnia, hypothyroidism, anxiety, depression, restless legs syndrome, and narcolepsy all produce fatigue and poor sleep. Some of them look identical to sleep apnea on the surface. Some of them co-exist with it.
Getting the right diagnosis means asking for complete testing, not settling for a single explanation when the symptoms do not fully resolve. Your sleep quality and your daily energy depend on getting this right.
