For those who have never experienced the persistent ringing of tinnitus, its intensity is hard to imagine—sometimes only a bad dream comes close.
Tinnitus can manifest as ringing, hissing, buzzing, or clicking sounds that only the affected person can hear. These sounds may be constant or intermittent, making daily life challenging.
Now, neuroscientists at the University of Oxford suggest that tinnitus and sleep are closely connected in the brain.
Their research points to a fundamental link between the two—a connection that has, until recently, largely gone unnoticed by scientists.
“Phantom Percept” Explained: When the Brain Tricks Us Into Sensing What Isn’t There
Many people encounter phantom percepts only while asleep, but for roughly 15 percent of the global population, a persistent noise—tinnitus—rings in their ears even during waking hours.
Tinnitus is the most common phantom percept worldwide, yet its cause and cure remain unknown, despite numerous theories.
Although many individuals with tinnitus report disrupted sleep and exhibit irregular sleep patterns, the potential link between tinnitus and this essential bodily function has only recently begun to emerge.
In 2022, Milinski led a review that the authors say is the first to examine, at a functional level, how sleep and tinnitus may influence each other.
The Oxford team proposed that the large, spontaneous waves of brain activity during deep, non-rapid eye movement (non-REM) sleep might suppress the neural activity that causes tinnitus.
To explore this idea, the researchers studied ferrets, whose auditory systems closely resemble those of humans. In experiments published in 2024, they found that ferrets with more severe tinnitus also experienced disrupted sleep.
“We could actually see these sleep problems appear at the same time as tinnitus after noise exposure,” Milinski told ScienceAlert. “This provided the first clear evidence of a link between the onset of tinnitus and disturbed sleep.”
Importantly, the ferrets with tinnitus exhibited hyperactive brain responses to sound. However, once they entered non-REM sleep, this overactivity was reduced.
These findings suggest that sleep may temporarily mask the effects of tinnitus by engaging the same brain circuits.
“Our findings suggest that deep sleep may help reduce tinnitus and could reveal natural brain mechanisms for regulating abnormal activity,” said Milinski.
While research in animals has its limitations, similar brain activity patterns are likely present in humans as well.
Since their 2022 review, Milinski notes that the field has grown quickly, with an increasing number of large-scale studies exploring how sleep, environmental factors, and tinnitus interact—not just in ferrets, but in humans too.
“I hope this research will raise awareness of tinnitus and pave the way for new approaches to treatment,” Milinski told ScienceAlert.
“Recognizing the impact of tinnitus—particularly in older adults, where hearing loss and tinnitus can heighten isolation and affect mental health—is critically important.”
Just last year, a study from China found that people with tinnitus struggled to suppress the hyperactive brain activity that occurs while awake as they transitioned into sleep.
However, during deep sleep, the tinnitus-related hyperactivity was reduced.
“This study highlights sleep as a crucial therapeutic target for breaking the 24-hour dysfunctional cycle of tinnitus,” concluded the researchers, led by Xiaoyu Bao of South China University of Technology.
At Oxford, Milinski and his team are now investigating how sleep may influence the development of tinnitus.
“Tinnitus can disrupt sleep, and poor sleep may, in turn, worsen tinnitus,” Milinski explained. “It may create a kind of vicious cycle, though I don’t believe it is unbreakable.”
“When we don’t get enough quality sleep, we become more susceptible to stress, and stress is one of the most powerful factors that can worsen tinnitus. In some cases, stress may even trigger it in the first place.”
Further research could not only pave the way for effective tinnitus treatments but also deepen our understanding of the complex mysteries of sleep itself.
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