Many individuals experience humming or groaning noises during sleep. This involuntary vocalization can be perplexing and sometimes concerning for their sleeping partners. These sounds, which occur without conscious awareness, are a distinct sleep-related event.
Understanding Sleep-Related Humming (Catathrenia)
Sleep-related humming is medically termed catathrenia, also known as nocturnal groaning. This condition involves producing monotonous, irregular groans or moans while asleep. The sounds are typically long and drawn-out, often occurring during the exhalation phase of breathing. These vocalizations can last for a couple of seconds or extend up to 40 seconds.
Catathrenia is distinct from other common sleep noises like snoring and sleep talking. Snoring occurs during inhalation, often due to vibrations in the soft tissues of the throat, whereas catathrenia sounds are produced during exhalation and originate from the vocal cords in the larynx. Unlike sleep talking, catathrenia is characterized by a consistent, non-verbal humming or groaning sound.
The individual making the sounds is usually unaware of them. These noises are often loud, potentially reaching volumes comparable to a vacuum cleaner, around 75 decibels, making them quite disruptive for anyone nearby. Catathrenia episodes tend to occur more frequently during rapid eye movement (REM) sleep, but they can also happen during non-REM sleep.
Potential Causes of Sleep Humming
The causes of catathrenia are not fully understood, as it is a relatively rare condition that has not been the subject of extensive large-scale studies. However, current theories suggest a link to abnormal respiratory patterns during sleep, particularly involving a prolonged exhalation. One leading hypothesis points to potential issues with neurons in the brain’s respiratory center, which may trigger these extended exhalations.
Other contributing factors may include anatomical features such as a small jaw size or narrow upper airways. These structural characteristics could influence airflow and vocal cord vibration during sleep. Some researchers also propose a possible genetic component, noting that catathrenia can sometimes run in families.
While catathrenia is classified as a sleep-related breathing disorder, it is separate from obstructive sleep apnea (OSA). Unlike OSA, catathrenia is not associated with temporary pauses in breathing or significant drops in oxygen saturation during sleep. Although some individuals with catathrenia may experience daytime sleepiness or fatigue, the condition itself is not known to cause major health complications.
When to Seek Medical Advice for Sleep Humming
If you or your sleep partner notice consistent humming or groaning during sleep, consulting a healthcare professional is recommended. While catathrenia is a benign condition with no direct health risk, it can significantly disrupt a sleep partner’s rest. The sounds can cause embarrassment, stress, and anxiety for the person experiencing them, and may negatively affect relationships.
Diagnosis involves a detailed medical history, a physical examination of the nose, mouth, and throat, and a sleep study (polysomnography). This overnight study helps confirm catathrenia by recording breathing patterns and the sounds produced, while also ruling out other conditions such as snoring, sleep talking, or sleep apnea. A video-polysomnography with audio recording is useful for accurate diagnosis.
Management focuses on alleviating disruptive symptoms. Lifestyle adjustments, such as earplugs or white noise machines for sleep partners, can help. Treatments include continuous positive airway pressure (CPAP) therapy, which uses mild air pressure to keep airways open. Oral appliances, similar to retainers, are also recommended to keep the jaw forward and airway open. Surgical options like tonsillectomy are considered if an upper airway obstruction is a contributing factor.