Meniere's Disease involves the ear, and produces symptoms of hearing loss, tinnitus (ringing in the ears), and vertigo (a form of dizziness). Nausea and vomiting often accompany the vertigo. Meniere's Disease is usually treated with medications, but that does not always help. Some research has pointed to an association of poor sleep quality and Meniere's Disease. Obstructive sleep apnea (OSA) can result in poor sleep quality and could worsen Menierie's.
This small study looked at the effect of 6 months of CPAP therapy on Meniere's Disease. All 20 patients had failed medication management of Meniere's Disease. All had OSA diagnosed with a sleep study, and all used CPAP therapy only. They did not restart their Meniere's medications during this study. Results showed that CPAP therapy by itself reduced the impact of the vertigo and the low-frequency hearing loss associated with Meniere's disease.
The reason that treating OSA may help Meniere's is unknown. The study authors speculate that elimination of low oxygen levels when asleep may be the factor that improves the Meniere's. I also wonder if elimination of the snoring helps.