What Is Catathrenia—Nocturnal Groaning?

Those moaning noises in your sleep may not necessarily be harmful but can be incredibly annoying.

If anyone sleeping near you has ever complained about groaning or moaning at night, you may have a rare sleep disorder called catathrenia. It makes you produce those sounds and hold your breath while you sleep. Sometimes referred to as "nocturnal groaning," catathrenia presents itself as a long, monotone groan or moan made involuntarily while the person is asleep. It may sound like a high-pitched squeak as well. Luckily, it's pretty harmless but can still be quite startling (especially when you're unaware someone is experiencing it).

Man making noises while sleeping

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Classifiing Catathrenia

The International Classification of Sleep Disorders, Third Edition, classified catathrenia as a rare chronic respiratory disorder. Still, experts disagreed on whether it should be classified as a parasomnia (a sleep disorder) or a respiratory issue, according to a 2015 review published in the journal Sleep Medicine.

Catathrenia affects all demographics, according to a 2021 chapter in Reference Module in Neuroscience and Biobehavioral Psychology. It often develops during adolescence or early adulthood. It's exceedingly rare and likely underreported because the sound is often misdiagnosed as snoring, sleep-talking, central sleep apnea, or another sleep-related breathing disorder.

According to a 2017 review published in the Journal of Clinical Sleep Medicine, studies had shown that catathrenia presented in only 0.17% of patients in a sleep center in Japan over 10 years or in 0.4% of patients in another study in Norway over one year.


Groaning is the primary manifestation of catathrenia. People with catathrenia will usually take a deep breath in before making a long moaning or groaning sound when they breathe out.

Groaning vs. Snoring

The groaning differs from snoring because it is made exclusively while exhaling and has a distinct sound, like something is blocking air from escaping the throat.

In the 2017 review, the authors wrote, "bed partners generally report hearing the person take a deep breath, hold it, then slowly exhale; often with a high-pitched squeak or groaning sound."

Catathrenia usually occurs during REM sleep, according to a 2017 article published in Sleep Medicine. REM sleep is the period of sleep that is associated with dreaming and memory consolidation. While less common, other periods of sleep can also be characterized by catathrenia.

The groaning can be interspersed with periods of normal breathing or happen continuously. Although the noises can be pretty loud—recorded between 40 decibels (a cricket) and 120 decibels (a chainsaw)—people with catathrenia are often completely oblivious. They mostly find out about their noisemaking when a family member, friend, or partner mentions it the following day, according to the 2015 review.

However, once the person with catathrenia is aware of their condition, they also tend to wake up from groaning, according to the review in the Journal of Clinical Sleep Medicine.

Other physical symptoms can include:

  • Dry mouth due to mouth breathing
  • Morning grogginess or headache
  • General fatigue and daytime sleepiness

Feeling tired during the day is a typical symptom. In fact, the 2017 article in Sleep Medicine reported that nearly half of the patients (44.7%) complained of feeling sleepy during the day.

According to the review in the Journal of Clinical Sleep Medicine, however, most people's biggest problem is the significant fear of distress to their bed partners. The sound can cause social embarrassment and have a negative effect on sex lives and relationships.

Causes of Nocturnal Groaning

Because catathrenia is so rare, experts aren't sure what causes it. But the groaning is thought to originate in the larynx, which houses the vocal cords.

"Whenever you make a sound, it's because of a vibration of the structures," Soroush Zaghi, MD, a sleep surgeon at The Breathe Institute, told Health. "In snoring, what's vibrating is the back of the throat…but in catathrenia, it's the vocal cords that are vibrating, so the sound is coming from the voice box."

Several possible suspects could cause this nocturnal (or nighttime) groaning. According to the Sleep Foundation, the following things may cause catathrenia: dysfunctional neurons (nerve cells) related to the part of your brain that controls breathing, small jaw size, small upper airways, and something called inspiratory flow disorder, which is when breathing doesn't change even when you try to breathe more. The Sleep Foundation also says that genetics could be involved, meaning catathrenia may run in the family.

But it's still unclear why people are groaning in the first place. There just aren't enough people who have catathrenia to give scientists solid evidence to determine the causes. And maybe it's not just one cause. Dr. Zaghi thought that catathrenia could be several different disorders with different causes.


The good news is that, while catathrenia may be annoying for a bed partner, it's pretty much harmless. Most people with catathrenia sleep just fine.

"We know it's annoying, but we're not exactly sure how to fix it," Dr. Zaghi said. "We have some guesses that maybe it's related to some kind of stress, something therapy or deep breathing exercises might help, but we're not going to push it too much because honestly, we don't know."

Some steps can be taken for those whose catathrenia impacts their sleep quality. Several studies, such as one published in 2017 in the Pulmonology Journal, have found that catathrenia could be successfully treated with a CPAP machine—a machine typically used to treat sleep-related breathing disorders that "uses mild air pressure to keep breathing airways open while you sleep," according to the National Heart, Lung, and Blood Institute.

One case study, published in March–April 2020 issue of Pulmonology Journal, looked at a 24-year-old individual with catathrenia. The patient was tested, and there were no other disorders or diseases that would be able to explain the symptoms. As a treatment, the patient received a CPAP machine. Not only did the CPAP control the number of times catathrenia occurred, but it also was effective at lower pressure settings than previously reported in the scientific literature.

It is recommended people with symptoms schedule a sleep study (polysomnography) to make sure that catathrenia is actually the issue. But positive airway pressure doesn't work for everyone. For some, asking their sleep partners to wear earplugs or use a white noise machine is an option that works well. But if that doesn't work, you may want to consider sleeping separately so you can wake up feeling fully refreshed and eager to greet your partner in the morning.

A Quick Review

Aside from being a potential nuisance, groaning and moaning in your sleep is not a health concern. Unlike with sleep apnea, which is much more common, people with catathrenia do not experience a decrease in oxygen levels during sleep. Low oxygen levels during sleep are a cause for concern because your organs can become damaged if they're not getting enough oxygen. If you or your partner think you may have catathrenia, it's worth getting checked out by a sleep specialist. You will be able rest assured knowing that the moaning in your sleep is nothing to worry about.

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