Catathrenia

Catathrenia, or groaning during sleep, is a parasomnia distinct from somniloquy (talking during sleep). The sound is produced during exhalation as opposed to snoring which occurs during inhalation. It is usually not noticed by the person producing the sound but can be disturbing to sleep partners. There appears to be no physical cause and is not exclusive to dreaming or REM sleep. Bed partners generally report hearing the person take a deep breath, hold it, then slowly exhale; often with a high-pitched "squeek" or groaning sound. Often the groaning occurs toward the end of sleep, within a couple hours of waking. Many speculate about a direct correlation to high stress.

Catathrenia has been defined as a parasomnia in the International Classification of Sleep Disorders Diagnostic and Coding Manual (ICSD-2), but there is debate about its classification, and its response to CPAP was unknown.

A study in the SLEEP Journal by Guilleminault C; Hagen CC; Khaja AM. Catathrenia: "para-somnia or uncommon feature of sleep disordered breathing?". SLEEP 2008;31(1):132-139.concluded:"Catathrenia may have subtypes related to sleep stage specificity or presence of sleep disordered breathing."and"CPAP and select soft tissue surgeries of the upper airway (often augmented with an oral appliance) successfully treated nocturnal groaning."

References

http://www.sleepeducation.com/Disorder.aspx?id=40

http://www.neurology.org/cgi/content/abstract/56/5/681

http://www.journalsleep.org/ViewAbstract.aspx?citationid=3456