Of all the sounds people make in their sleep, catathrenia is one of the strangest to witness. It is a long, groaning or moaning sound made on the out-breath — the sleeper draws a slow breath in, then releases it with a drawn-out, sometimes eerie groan that can last several seconds and repeat for stretches of the night. Almost no one knows they do it; they find out from a worried partner. (This is general information, not medical advice.)
What catathrenia is
Catathrenia, sometimes called nocturnal groaning, is a sleep-related breathing phenomenon classed among the parasomnias. The pattern is distinctive: a deep inhalation, a pause, then a prolonged vocalized exhale — the groan. It tends to occur in clusters, often during the later part of the night, and the sound is produced as air passes the vocal cords on the way out.
The person is unaware, breathing is otherwise regular between episodes, and they typically wake feeling fine — it is the bed partner who loses sleep over it.
How it differs from snoring and other sounds
It is easy to lump any nighttime noise together, but catathrenia is its own thing:
- Snoring happens on the in-breath, as turbulent air vibrates relaxed tissues. Catathrenia happens on the out-breath, as a vocalized groan. (Why do I snore?)
- It is not sleep talking, which involves words or mumbling, not a sustained tone. (Why do I talk in my sleep?)
- It is not sleep apnea, though the two can be confused — which is exactly why it is worth a professional check.
Is it dangerous?
For most people, catathrenia is benign — it does not harm the sleeper, who usually sleeps well through it, and it is not a sign of a serious disorder on its own. Its main cost is social: the sound can genuinely disturb a partner and cause embarrassment.
That said, because groaning and breathing noises at night can overlap with other sleep-related breathing problems, it is sensible to have it evaluated rather than assumed benign — especially if there is also loud snoring, witnessed breathing pauses, or daytime sleepiness, which point toward apnea. (Signs of sleep apnea.)
What helps
There is no single proven cure, and because it is harmless, treatment is often about reassurance and ruling out look-alikes:
- Get a sleep assessment if the sound is frequent, if a partner is worried, or if there are any apnea signs — the first job is confirming what it actually is.
- Address contributors where present — stress, irregular sleep, and alcohol can worsen many sleep phenomena, so the fundamentals help. (How to sleep better.)
- Discuss options with a sleep specialist — some people are trialed on airway-pressure therapy with variable results; this is an individual decision, not a general recommendation.
- Protect the partner's sleep in the meantime — earplugs or white noise are reasonable stopgaps. (White noise for sleep.)
If you are unsure where your nights stand, the free Titan Sleep Score quiz is a quick first pass — though a strange recurring sound your partner is hearing is best confirmed by a sleep professional.
FAQ
What is catathrenia? Catathrenia, or nocturnal groaning, is a sleep-related breathing phenomenon in which the sleeper makes a long, groaning sound on the out-breath — a deep inhale followed by a prolonged, vocalized exhale. It occurs in clusters, often later in the night, and the person is usually unaware of it.
Is catathrenia the same as snoring? No. Snoring happens on the in-breath as air vibrates relaxed tissues, while catathrenia is a groaning sound on the out-breath as air passes the vocal cords. They are different phenomena, though both are nighttime sounds and can be confused by a listener.
Is catathrenia dangerous? For most people it is benign and does not harm the sleeper, who typically sleeps well through it. Its main impact is disturbing a bed partner. Because it can be confused with other sleep-related breathing problems, it is still worth having evaluated, especially alongside loud snoring, breathing pauses, or daytime sleepiness.
How do you treat catathrenia? There is no single proven cure. Management focuses on a sleep assessment to confirm what it is and rule out apnea, addressing contributors like stress, irregular sleep, and alcohol, and discussing individual options with a sleep specialist. In the meantime, earplugs or white noise can protect a partner's sleep.
The bottom line
Catathrenia is a long groan on the out-breath during sleep — eerie to hear, usually harmless to the sleeper, and distinct from both snoring and apnea. The sensible move is a sleep assessment to confirm it is catathrenia and not something that mimics it, then reassurance and protecting your partner's rest. It is more a sound worth understanding than a danger to fear.