Why Do I Moan in My Sleep?

Key Takeaways

• Sleep moaning (catathrenia) is a parasomnia involving prolonged groaning during exhalation, most common during REM and deep sleep.
• It's generally harmless to the person moaning but can significantly disrupt a bed partner's sleep.
• Catathrenia is distinct from snoring, sleep talking, and sleep apnea, though it can coexist with these conditions.
• CPAP therapy and positional changes are the most studied treatments, with moderate success rates.
• A sleep study is the gold standard for diagnosing catathrenia and ruling out other sleep disorders.

What Is Catathrenia (Sleep Moaning)?

A parasomnia, not a dream response

Catathrenia falls under the category of parasomnias, which are unusual behaviors during sleep. Unlike sleep talking (which involves speech) or nightmares (which involve distress), catathrenia produces monotone, drawn-out sounds during exhalation. You take a deep breath in, then release it slowly with a groan, moan, or humming noise that can last 2 to 50 seconds.

The International Classification of Sleep Disorders classifies catathrenia as a "sleep-related breathing disorder" in some editions and a "parasomnia" in others. This classification debate reflects how poorly understood the condition remains. What researchers do agree on: the sounds originate from partial closure of the vocal cords during expiration, not from dreaming or pain.

What it sounds like

Bed partners describe catathrenia sounds as groaning, moaning, humming, or even a high-pitched squeal. The sound typically follows a pattern: a deep inhalation, a long pause, and then a slow, vocalized exhalation. Episodes can cluster in groups, lasting anywhere from a few minutes to over an hour. People who make noises in their sleep often don't realize the variety of sounds they produce.

Why Do People Moan in Their Sleep?

Airway dynamics during exhalation

The leading theory involves your vocal cords partially closing as you exhale during sleep. When air pushes through a narrowed glottis (the opening between your vocal cords), it creates vibration and sound. Think of it like air escaping from a partially tied balloon: the restricted opening makes noise.

A study in the journal Sleep used laryngoscopy during sleep to confirm that catathrenia sounds originate from vocal cord adduction (closing) during expiration. This distinguishes it mechanically from snoring, which happens during inhalation when the soft palate vibrates.

Brain activation during sleep stages

Catathrenia occurs most frequently during REM sleep, though it can also appear during non-REM stages. During REM sleep, your brain is highly active while your body remains mostly paralyzed (a state called atonia). However, your breathing muscles partially escape this paralysis. Researchers believe the brain sends irregular signals to the vocal cords and breathing muscles, creating the conditions for sound production.

This explains why sleep moaning comes and goes throughout the night. It clusters during specific sleep stages rather than persisting continuously.

Possible contributing factors

While the exact cause remains unclear, several factors may increase the likelihood of catathrenia:

• Small jaw or specific facial bone structure that narrows the airway
• Family history (some studies suggest a genetic component)
• Stress and sleep deprivation, which alter sleep architecture
• Sleeping on your back, which allows the tongue and soft tissues to fall backward
• Nasal obstruction that changes breathing patterns

How Sleep Moaning Differs From Other Sleep Sounds

Catathrenia vs. snoring

Snoring happens during inhalation when relaxed throat tissues vibrate. Catathrenia happens during exhalation when the vocal cords partially close. This is the key distinction. Snoring tends to be continuous and rhythmic. Catathrenia follows a pattern of deep breath in, long pause, then vocalized breath out. People who sleep with a snorer can usually tell the difference once they know what to listen for.

Catathrenia vs. sleep talking

Sleep talking involves recognizable words, phrases, or mumbling and originates from speech centers in the brain. Catathrenia produces no words. The sounds are monotone and mechanical, more like a sustained vocalization than an attempt at communication. If you're producing actual words, that's somniloquy, not catathrenia.

Catathrenia vs. sleep apnea

Sleep apnea involves repeated pauses in breathing followed by gasping or choking sounds. The sounds of sleep apnea are tied to airway obstruction and oxygen desaturation. Catathrenia doesn't typically cause oxygen drops or breathing pauses, though the two conditions can coexist. A sleep study can differentiate between them.

Who Gets Catathrenia?

Demographics and prevalence

Catathrenia is considered rare, but prevalence data is limited because many cases go undiagnosed. A study in Sleep Medicine found that it affects both men and women roughly equally, with onset typically in adolescence or early adulthood. Many people live with it for years before seeking help, often only after a bed partner raises concerns.

The bed partner problem

Here's the irony of catathrenia: the person moaning usually sleeps fine. They don't wake themselves up, they don't experience oxygen drops, and they rarely feel tired the next day. The bed partner, however, may develop significant sleep anxiety or chronic sleep loss from the repetitive sounds. This makes catathrenia a shared sleep problem, even though only one person produces the sounds.

How Catathrenia Is Diagnosed

Polysomnography is the gold standard

A sleep study (polysomnography) records brain waves, eye movements, muscle activity, airflow, and sound during sleep. For catathrenia, the study reveals the characteristic pattern: sound production during exhalation, clustering during REM sleep, and absence of oxygen desaturation. This test also rules out sleep apnea, which can sound similar to an untrained ear.

Audio recordings help too

Before scheduling a formal sleep study, your doctor may ask you (or your partner) to record the sounds at home. Smartphone recordings capture enough detail for a sleep specialist to distinguish catathrenia from snoring or other sounds. Bring these recordings to your appointment.

How to Manage Sleep Moaning

Positional therapy

Since catathrenia may worsen when sleeping on your back, switching to side sleeping can reduce episodes. Back sleeping allows the tongue and soft palate to fall backward, potentially contributing to vocal cord narrowing. A body pillow or tennis ball taped to the back of your shirt can help you stay on your side throughout the night.

CPAP therapy

Continuous positive airway pressure (CPAP) keeps your airway open with a steady stream of air. A study in the journal Sleep found that CPAP reduced or eliminated catathrenia sounds in several patients. The pressurized air prevents the vocal cords from closing during exhalation. If you also have sleep apnea, CPAP addresses both conditions simultaneously.

Stress reduction and sleep hygiene

Stress and sleep deprivation can alter your sleep architecture, potentially increasing the frequency of catathrenia episodes. Consistent sleep schedules, deep sleep optimization, and stress management techniques like meditation may help reduce episodes. While these aren't cures, they support overall sleep quality.

Protecting the bed partner

Until the moaning is managed, your bed partner needs protection. White noise machines can mask the sounds effectively. Earplugs designed for sleeping block repetitive low-frequency sounds while still allowing alarm clocks through. In some cases, the Scandinavian sleep method (separate blankets, or even separate sleeping surfaces) preserves the relationship while solving the noise problem.

When Sleep Moaning Needs Medical Attention

Signs that warrant investigation

See a sleep specialist if your moaning is accompanied by:

• Daytime sleepiness or fatigue despite adequate sleep hours
• Gasping, choking, or breathing pauses observed by your partner
• Morning headaches or dry mouth
• Sudden onset of moaning sounds later in life (after age 50)
• Any other neurological symptoms like tremors or difficulty swallowing

Late-onset catathrenia or moaning combined with neurological symptoms could indicate an underlying condition that needs evaluation. Your doctor may order imaging or refer you to a neurologist.

Sleep Better With Real Data

Understanding why you moan in your sleep starts with understanding your sleep itself. Are you getting enough deep sleep? Is stress shifting your sleep architecture? Are underlying health markers affecting your rest?

Superpower's at-home blood panel measures over 100 biomarkers connected to sleep quality, stress response, and neurological health. Pair that data with a conversation with your doctor, and you'll have a clearer picture of what's happening when the lights go out. Start your Superpower membership and turn confusion into clarity.