Sleep Disturbances Associated With Hidden Hearing Loss: Insights From Human Data and a Mouse Model of Sleep Fragmentation.

Background: Sleep disorders have been associated with auditory dysfunction. However, the specific effects of sleep fragmentation (SF) on the peripheral auditory system and the underlying mechanisms remain unclear.

Methods: Data from the National Health and Nutrition Examination Survey (NHANES) were analyzed to examine the association between sleep disturbances and difficulties in speech perception in noisy environments among participants with normal audiograms. Additionally, an SF mouse model was used to assess the impact of sleep disruption on auditory function and cochlear pathology. Auditory brainstem response (ABR) testing, immunofluorescence staining, and transmission electron microscopy were performed to evaluate the auditory system.

Results: NHANES data revealed that individuals with sleep disorders, even with normal audiograms, were more likely to experience difficulties in speech perception in noisy environments. In the mouse model, chronic SF led to a significant decrease in the amplitude and a prolonged latency of ABR wave I, without detectable changes in hearing thresholds. Immunofluorescence staining revealed a significant decrease in the number of ribbon synapses in inner hair cells and an increase in orphan ribbons. Moreover, electron microscopy demonstrated myelin damage in the auditory nerve fibers.

Conclusions: Sleep fragmentation induces subtle damage to the auditory system, particularly affecting inner hair cell synapses and auditory nerve fibers, which may underlie difficulties in speech recognition in noisy environments, a potential indicator of hidden hearing loss.