Can't Stay Asleep? Your Breathing Might Be Waking You Up

You fall asleep without much trouble. Then, sometime after midnight, you're awake. Maybe you check the clock, roll over, and drift off again. Maybe you lie there for an hour. This repeats, some nights two or three times, and by morning you feel like you barely slept at all. If someone asks why you woke up, you have no answer. There was no noise, no bad dream, no obvious reason. You just woke up.

This pattern has a name: sleep maintenance insomnia, trouble staying asleep rather than falling asleep. It's the most common insomnia complaint, affecting roughly 60 percent of people with insomnia. And it's almost always attributed to the usual suspects: stress, anxiety, aging, too much screen time, poor sleep habits.

Those explanations are sometimes right. But there's another cause that hides remarkably well behind this exact complaint, and it's one most people never consider because it doesn't match anything they associate with the condition. Your breathing may be waking you up, dozens of times a night, without you ever knowing it.

The finding that reframes the problem

Here's a piece of research that should change how we all think about middle-of-the-night waking.

In a study of people with chronic insomnia, patients who had none of the classic signs of sleep apnea, no reported loud snoring, no witnessed breathing pauses, no obvious daytime sleepiness, researchers monitored their sleep objectively and looked at what happened in the moments right before each awakening. The result was striking: about 90 percent of their observed nighttime awakenings were preceded by a breathing event, an apnea, a hypopnea (shallow breathing), or a subtle respiratory effort-related arousal.

These patients had no idea their breathing was involved. They described exactly what you'd expect: waking up for no reason. But the objective data showed a reason, one happening below the threshold of awareness. Their airway was destabilizing, their body was responding, and the awakening followed.

That doesn't mean every case of middle-of-the-night waking is a breathing problem. But it does mean that "I just wake up and I don't know why" is a symptom worth taking seriously rather than accepting as a quirk of a stressful life.

COMISA: when insomnia and sleep apnea travel together

Sleep medicine has a name for the overlap of these two conditions: COMISA, short for co-morbid insomnia and sleep apnea. It's increasingly recognized as its own clinical entity rather than two unrelated problems that happen to coincide ^{[1, 2]}.

The numbers are higher than most people would guess. Roughly 30 to 40 percent of people with insomnia have undiagnosed obstructive sleep apnea alongside it, and conversely, about 30 to 50 percent of people with sleep apnea report significant insomnia symptoms ^{[1, 2, 3]}. That's not a rare coincidence; it's a large, systematically overlooked population. And COMISA isn't merely the sum of two problems. People with both tend to have worse daytime functioning, lower quality of life, and higher rates of cardiovascular and psychiatric conditions than people with either condition alone ^[4].

Part of why COMISA hides is that the two conditions can mask each other. Someone who identifies as "an insomniac" has a ready explanation for their fragmented nights and never pursues a sleep apnea evaluation. Meanwhile, the classic sleep apnea profile most clinicians and patients have in mind, a heavy snorer who's visibly sleepy all day, doesn't match the wired, exhausted, can't-stay-asleep insomnia patient at all. So the airway never gets investigated.

Why the difference matters so much for treatment

This is the part with real practical stakes, because insomnia and sleep apnea respond to entirely different treatments, and treating only one half of a COMISA case tends to disappoint.

The first-line treatment for chronic insomnia is CBT-I, cognitive behavioral therapy for insomnia, a structured, evidence-based program that addresses the thoughts and behaviors keeping people awake. It's genuinely effective and considerably more durable than sleeping pills. But CBT-I is designed to unwind conditioned hyperarousal and unhelpful sleep habits. It cannot open a collapsing airway. If your awakenings are being triggered by breathing events, no amount of stimulus control or sleep restriction will stop them.

Conversely, CPAP, the standard treatment for sleep apnea, keeps the airway open and stops the breathing events, but it does nothing for the learned anxiety and hyperarousal that chronic insomnia builds up over months and years. Many people with COMISA who start CPAP find their breathing improves while their insomnia persists; studies suggest a substantial share continue to have insomnia symptoms even with regular CPAP use ^[5].

The evidence increasingly points toward treating both. Combined treatment with CBT-I and positive airway pressure produces better outcomes than either alone in COMISA patients ^{[2, 6]}. There's also a helpful synergy: treating the insomnia first or alongside tends to improve people's acceptance of and adherence to CPAP, which is often the hardest part of apnea treatment ^{[1, 6]}. Each therapy makes the other work better.

The practical implication for you is simple. If you've been treated for insomnia and it hasn't worked, that's meaningful information. It may not mean the treatment was wrong or that you're a difficult case. It may mean only half the problem was being addressed.

A caution about sleeping pills

Because sleep maintenance insomnia is so frustrating, many people end up on prescription sleep medication, or reach for over-the-counter sleep aids. If there's undiagnosed sleep apnea underneath, this deserves careful thought and a conversation with your doctor.

The most important issue is straightforward: sedatives don't treat airway obstruction. If breathing events are causing your awakenings, a sleeping pill may blunt your awareness of them without addressing the underlying problem, so the apnea continues doing its damage to your heart, blood pressure, and metabolism, just more quietly. Masking a symptom isn't the same as treating a cause.

There's also a direct safety question, and here the evidence is more nuanced than the internet suggests. Older studies of benzodiazepines found they could prolong breathing events and worsen overnight oxygen levels in people with sleep apnea, and benzodiazepine use in OSA patients has been associated with an increased risk of adverse respiratory events ^{[7, 8]}. A recent, comprehensive network meta-analysis, however, found that most hypnotic medications did not uniformly worsen the apnea-hypopnea index compared with placebo, though one benzodiazepine, temazepam, did reduce oxygen saturation during sleep ^[9]. The researchers' conclusion is a sensible one: treatment should be individualized, with careful weighing of risks and monitoring of respiratory status, particularly with benzodiazepine-type agents or in people with severe apnea ^[9].

The takeaway isn't that sleep medication is always dangerous. It's that taking a sedative to solve persistent night waking, without knowing whether a breathing problem is behind it, means potentially treating the wrong thing and, in some cases, adding a risk you don't need. Finding out what's actually causing the awakenings should come first.

What to do if this sounds like you

If you can't stay asleep and the standard explanations haven't panned out, here's a reasonable path forward.

Raise the possibility of sleep apnea directly with your doctor, even if, especially if, you don't fit the stereotype. You don't have to snore loudly or feel sleepy during the day to have it. Mention the pattern: repeated awakenings, no obvious trigger, unrefreshing sleep, and any accompanying signs like morning headaches, nighttime urination, or hard-to-control blood pressure.

Screening is simple. Questionnaires such as the STOP-Bang help gauge your risk, and diagnosis can often be made with a home sleep test, a small device you wear overnight in your own bed that measures airflow, breathing effort, and oxygen levels. This has removed most of the old friction of an overnight lab stay.

If a home test comes back normal but your symptoms persist, that's not necessarily the end of the inquiry. Home tests are good at detecting moderate-to-severe apnea but can miss subtler patterns, such as respiratory effort-related arousals and upper airway resistance, that a full in-lab sleep study is better equipped to catch. Persistent unexplained symptoms plus a normal home test is a reason to ask about further evaluation.

If you're diagnosed with both, seek treatment for both. The most effective approach for COMISA addresses the airway and the insomnia together, rather than picking one and hoping the other resolves.

Don't stop or start medication on your own. Any decisions about sleeping pills, particularly if sleep apnea is suspected or confirmed, belong in a conversation with your clinician.

The bottom line

Sleep maintenance insomnia, the frustrating pattern of waking repeatedly and not knowing why, is usually blamed on stress, habits, or age. Sometimes that's right. But a large and under-recognized share of people with this complaint have obstructive sleep apnea driving their awakenings, often without any of the classic signs, and in one study of insomnia patients without typical apnea symptoms, roughly 90 percent of observed awakenings were preceded by a breathing event. Insomnia and sleep apnea overlap far more often than most people realize, a combination now called COMISA, and it matters because the two need different treatments. CBT-I won't open an airway; CPAP won't undo conditioned hyperarousal. If you've been treating insomnia without success, the missing piece may be your breathing, and that's a very findable, very treatable answer.

Frequently asked questions

This article is for general education and isn't a substitute for individual medical advice. If you have persistent trouble staying asleep, or questions about sleep apnea, insomnia, or sleep medications, talk with a qualified clinician.