Sleep apnea. Narcolepsy. Restless leg syndrome. REM sleep behavior disorder. Fatal familial insomnia. Nightmare disorder. The list of sleep and related disorders is long, and while some, like insomnia, are common enough that we all know about them, this dark corner of medical conditions also features some disorders that are so little-known that most people outside of the medical profession will never have heard of them.

Catathrenia is one of these rare sleep-related conditions. Its main symptom may induce more than its fair share of fun-poking on all who hear patients in their sleep, but catathrenia is a very real phenomenon that continues to puzzle scientists.
What is catathrenia?
Even that continues to be up for debate, as catathrenia has been described as a sleep disorder, a respiratory (breathing) disorder, a parasomnia (unusual sleep-related behavior), and even simply as a "phenomenon" in the medical literature. While the International Classification of Sleep Disorders Diagnostic and Coding Manual (ICSD-2) considered catathrenia as a parasomnia, its exact nature still very much continues to be up for debate.
One thing that is very clear, however, is the main symptom of catathrenia — a deep groaning when exhaling during sleep, usually following a brief pause in breathing after inhalation. This groaning during sleep sounds, according to the partners of people who have it, quite similar to the kinds of sounds a person may make as they are being intimate with someone. While the exact cause of catathrenia remains a puzzle, the actual groaning sound itself appears to come from the voice box and specifically the vocal cords, which makes the disorder fundamentally different from snoring, which actually originates in the back of the throat.
Among the key facts about catathrenia you'll want to be aware of if it has recently come to your attention that you groan during your sleep, or if your partner groans during their sleep, are:
- Besides groaning during sleep, which can strike during all stages of the sleep cycle, people with catathrenia may sound hoarse when they wake up because their vocal cords have been exercising all night.
- Patients with catathrenia may get slightly less oxygen as they groan in their sleep.
- Though catathrenia doesn't usually lead to debilitating symptoms for patients, some suffer from excessive daytime sleepiness, indicating that they are not getting good-quality rest at night. This kind of all-encompassing fatigue can severely impact a person's quality of life.
- Living with a partner who has catathrenia can also be hard — the groaning sound can physically keep a partner up much of the night, and also cause worry.
- It appears that catathrenia — an extremely rare disorder — is more likely to affect men, and that the groaning usually first emerges during adolescence. Patients were also found to have unusually small jaws that often lead to the need for tooth extractions, which may help scientists get to the bottom of its exact cause in future.
- Most of the time, the impact of catathrenia is mostly social; patients worry that their nocturnal groaning disturbs their partners or anyone else who can hear them sleep. Because the disorder doesn't typically have a physically dangerous impact (something that would only be true for those patients who suffer from debilitating fatigue), studying catathrenia has not been a high priority.
How is catathrenia treated or managed?
The process of diagnosing catathrenia is likely to be long, and you will require a sleep study to rule out other possible causes. Once diagnosed, CPAP (continuous positive airway pressure) appears to be the best treatment option. CPAP machines offer a constant flow of air pressure to facilitate proper breathing.
Patients and their partners may also benefit from minimally-invasive options to manage catathrenia — a humidifier may reduce the groaning and help with any hoarseness, while earplugs are an old-fashioned but effective solution for partners.
As research advances, scientists will hopefully figure out how to help the approximately 40 percent of catathrenia who are chronically unable to attain a restful night's sleep. In the meantime, people who have catathrenia will strongly want to consider connecting with others who experience nightly groaning — as only they can truly understand the reality of living with a medical disorder that is still so poorly understood.