<unk>  itself is not considered life-threatening. 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. Common characteristics in reported cases There are reported characteristics that are shared among patients with<unk> . The main characteristics are: * Vocal sound: Sounds are usually a short or long vocalisation of the same letter (mainly an a, e, o sound or something in between). Contrary to snoring which has only formants,<unk>  has also harmonics and show more regular and similar patterns between nights. *Onset of groanings: Groanings tend to begin in childhood, adolescence or early adulthood. The ICSD-2 established the age of onset ranging from 5 to 36 years. *Consistency from night to night. *Appearing during expiration: The sounds show up exclusively on expiration and are interrupted during inspiration. *Unawareness of the problem: Patients usually sleep normally despite the sounds and the effort to breath. However, bed partners and entourage are on one hand disturbed by the emitted noises during their sleep and on the other hand concerned about the pathological meaning of the disease. The latter highlights the importance of reassuring entourage about the benignity of the disease. *No predisposing factors: No clear predisposing factors or aetiology have been demonstrated. *The duration of the groaning sound varies from two to 49 s. There are a few other similarities amongst people with<unk>  that have not yet been studied properly: * Many people with<unk>  mention that they also have some form of stress or anxiety in their lives. * People with<unk>  themselves do not feel like they are experiencing a sleep apnea; the breath-holding appears to be controlled through the unconscious. Oxygen desaturation during a<unk>  episode is usually negligible. * Many took part in sports activities during teens and twenties some which required breath-holding which included many types of sports such as swimming and even weight lifting. They find a certain level of comfort in breath-holding, and often do it while awake. * Observations have been made of instances of breath holding during daily activities that require concentration. * Some people with<unk>  recalled having lucid or stress dreams during their<unk>  episodes during their sleep. * Some people with<unk>  complain of having a painful chest upon waking from sleep. Certain side effects include sore throat, fatigue, and dizziness. Discrepancies among reported cases * Sound duration: The duration of the sound varies among patients. While the ISCD-2 established limits between 2 and 49 s, authors have described other ranges including short duration as of 0.5 s. Review of reported cases indicates two types of patients whose produced sound can either be short lasting (0.5 to 1.5 s) or longer lasting (2 to 20 s). Nonetheless, it is not clear if the sounds are in fact single long noises fragmented by brief expirations. * Sound intensity: Patients show a large variability in sound intensity ranging from 40 dB to 120 dB. In addition, sounds can also be long and soft as well as short and loud. *Onset time of the noise during the night: The ISCD-2 established latency of noises after falling asleep ranging from 2 to 6 h. However, in some published cases the onset time of the noises is reported as being shorter (3 min ). *Association with respiratory disorders. *Response to continuous positive airway pressure (CPAP) treatment: The response to CPAP treatment partly depends on respiratory disorders. Patients with respiratory dysrhythmia may show poor to no improvements. CPAP in combination with drugs may also obtain unsatisfactory results. For other patients there is an excellent response to CPAP treatment (e.g., for young women patients with<unk>  over a 5-year period, patient with OSA and pulmonary hypertension, and others ). *Predominance of REM or NREM:<unk>  typically, sometimes even exclusively, occurs during REM sleep, although it may also occur to a lesser degree during NREM sleep. The predominance of REM or NREM sleep during which noises occurs varies from patient to patient. For some cases, a REM predominance has been reported whereas it is the opposite for others. Other reports indicated that sounds may occur at any time during sleep.
Catathrenia
Orthostatic hypertension
Cinchonism
Labile hypertension
Paroxysmal hypertension
Hypertensive urgency
Benign hypertension
Silent sinus syndrome