Obstructive Sleep Apnoea is a common medical condition in which the throat narrows or collapses repeatedly during sleep. Symptoms include loud snoring and a stoppage of breathing during sleep which causes intermittent hypoxia, a lack of oxygen.
Treatment is often the use of a continuous positive airway pressure (CPAP) generator. While beneficial in maintaining oxygen levels in people with obstructive sleep apnoea, CPAP generators are quite loud, generating on average 68 dB(A) of noise when in use. Interestingly, snoring itself can generate up to 65db(A) of noise.
Multiple studies report a relationship between sleep apnoea and hearing impairment, including a link between the severity of the sleep apnoea and the degree of hearing loss experienced. The exact relationship and how the hearing loss is caused is unclear.
The current guidelines on occupational noise exposure published by Safe Work Australia state that over an eight-hour shift a worker can’t be exposed to more than 85dB(A) of continuous noise. If this noise level or period of time is exceeded, the worker is at risk of a noise-induced hearing loss. If we use this as a guide to whether snoring or a CPAP machine could cause a noise-induced hearing loss the scenario becomes unlikely.
However, exposure to the noise of a CPAP generator or snoring for longer than 8 hours could possibly cause a noise-induced
Sleep apnoea causes an upper airway obstruction leading to snoring or a stoppage of breathing, meaning that the person cannot inhale enough oxygen. This lack of oxygen causes an apnoeic crisis, where not enough oxygen is getting to the persons’ vital organs and brain.
Often the person will wake up at this point so that they can clear the obstruction and breathe better. While the body is not receiving enough oxygen during this crisis, an ischaemic injury, or damage to the tissues due to lack of oxygen, can occur. Our cochlea could be one of these organs damaged by an ischaemic injury during a time of apnoeic crisis. This damage to the cochlea, and in particular to the hair cells, could cause a hearing loss. More research is required in this area to determine if cochlear damage is the cause of hearing loss in people with sleep apnoea.
Irrespective of which theory proves correct, it is easy to see the importance of CPAP machines, to stop snoring, sleep apnoea and to prevent apnoeic crisis, giving everybody a good night’s sleep and potentially protecting our hearing too.