Study reveals how naps, snoring, and sleep apnea interplay to temporarily amplify tinnitus, uncovering critical links to somatosensory modulation and offering new insights into managing this condition.
Study: Why does tinnitus vary with naps? A polysomnographic prospective study exploring the somatosensory hypothesis. Image Credit: jittawit / Shutterstock.com
In a recent study published in the journal Hearing Research, scientists characterize somatosensory modulations that may contribute to nap-induced increases in tinnitus loudness in patients.
What causes tinnitus?
Tinnitus, which affects about 14% of the global population, is a medical condition defined as the conscious awareness of a tonal or composite noise for which there is no identifiable corresponding external acoustic source. Tinnitus patients typically hear a constant or transient ringing or buzzing noise in one or both ears.
Various factors may contribute to the perception of tinnitus, including somatosensory factors, stress, noise, specific food intake, and atmospheric pressure changes. Another crucial modulator is napping sleep, which is reported by about 33% of all tinnitus patients. In fact, many tinnitus patients report experiencing increased tinnitus loudness following a nap.
Previous research suggests that somatosensory modulations of tinnitus may contribute to nap-induced changes in tinnitus loudness, which may be attributed to various physiological events. Bruxism during a nap, for example, which refers to grinding, gnashing, or teeth clenching, can stimulate the trigeminal nerve and subsequently induce somatosensory modulation of tinnitus upon awakening.
Sleeping in inclined positions for extended durations can modulate the cervical and masticatory muscle tonus, another somatosensory source of tinnitus modulation. Snoring and sleep apnea may also contribute to nap-induced tinnitus modulation by causing tensor veli palatini muscle dysfunction.
About the study
In the current study, researchers investigate whether nap-induced increases in tinnitus perception are due to somatosensory modulations and the role of the central or autonomic nervous systems in these patterns. To this end, 37 tinnitus patients reporting frequent induction of tinnitus following naps were included in the study.
All study participants attempted six nap attempts over two days, during which they underwent polysomnographic examinations. Audiological and kinesiologic tests were conducted before and after each nap attempt.
The participants attempted three naps on each day. On both days, the first nap started at 11 A.M., followed by the second and third naps at 2 P.M. and 4 P.M.
Important observations
The study recorded and analyzed 197 naps, with a significant increase in tinnitus loudness observed following each nap. However, a reduction of 23% in tinnitus loudness was observed after some nap attempts.
A significant reduction in tinnitus loudness was observed both at the first and second study breaks of the day. In the first break, participants had their lunch, whereas no food intake occurred during the second break. This finding indicates that food intake is not associated with the increased tinnitus loudness.
Among various sleep stages, light and deep sleep were observed in 85% and 7% of nap attempts, respectively. Random eye movement (REM) sleep was not observed in any of the nap attempts.
A significant positive association was observed between light and deep sleep durations and tinnitus loudness. However, no significant association was observed between total nap duration and tinnitus loudness.
Significant positive associations were observed between snoring duration and tinnitus loudness and between snoring sound intensity and tinnitus intrusiveness. Likewise, a significant positive association was observed between the number of apnea and hypopnea episodes during sleep and tinnitus intrusiveness; however, this association was not observed for tinnitus loudness. Overall, significant positive associations between the total duration of snoring and sleep apnea during naps were observed with tinnitus loudness and intrusiveness.
No significant impact of napping position and bruxism during nap was observed on tinnitus loudness or intrusiveness.
Study significance
The current study is the first to demonstrate and quantify nap-induced increase in tinnitus loudness in a controlled clinical environment. The study findings reveal that snoring and apnea during naps can further increase the negative effect of naps on tinnitus loudness and intrusiveness, thus suggesting the involvement of the tensor veli palatini muscle in the modulatory process. Importantly, nap-related tinnitus modulation is temporary, and a significant reduction in tinnitus loudness can be experienced between naps.
Naps can significantly reduce the ipsilateral and contralateral measurements of resonance frequency, which could be due to the residual effect of middle-ear pressure elevation during sleep. However, the current study did not observe any association between resonance frequency reduction and nap-induced tinnitus modulation.
The researchers did not observe an association between nap-induced tinnitus and somatosensory modulation involving the temporomandibular joint and cervical areas. It is possible that a nap-induced tinnitus modulation is a hidden form of somatosensory modulation, as snoring and sleep apnea events are often related to tensor veli palatini muscle dysfunction.
Journal reference:
- Guillard, R., Phillipe, V., Hessas, A., et al. (2024). Why does tinnitus vary with naps? A polysomnographic prospective study exploring the somatosensory hypothesis. Hearing Research. doi:10.1016/j.heares.2024.109152.