How To Sleep Soundly Without Hearing Loss

It is commonly thought that our brains are inactive while we sleep, but research shows that our brains are more responsive than we think. While we do hear while we sleep, our brains act as a filter, deciding whether we should wake up or continue sleeping. Our brains are more responsive to loud, unusual, or important sounds, such as our name being called, and we are more easily woken during light sleep than deep sleep.

The brain decides what sounds to block out

The brain acts as a filter while we sleep, deciding whether we should wake up or continue sleeping. This decision-making process is dependent on a variety of factors.

Firstly, the brain responds more quickly to loud sounds. For example, a loud bang is more likely to wake us up than the sound of a mosquito buzzing.

Secondly, the type of sound matters. Unusual or unfamiliar sounds are more likely to wake us up as our brain interprets them as a potential threat. A 2019 study in the Human Nature Behavior Journal found that even during sleep, the brain pays more attention to some sounds than others. The study showed that participants paid more attention to a meaningful voice than one speaking gibberish.

Thirdly, the brain is also more likely to wake us up to sounds it considers important, such as our name. A 2022 study by Blume et al. found that unfamiliar voices elicited stronger brain responses than familiar ones.

Lastly, individual differences in sound sensitivity play a role. Someone who is very sensitive to noise might find it difficult to sleep in a noisy environment, while someone who is not sound-sensitive will not be affected by noise in the same way.

Louder sounds are more likely to wake us up

While it is true that our brains remain responsive to our surroundings while we sleep, they are better at fending off noises during certain sleep stages. During the initial stages of sleep, the brain's responsiveness to the outside world is higher, but this awareness diminishes significantly in deeper stages.

Loud sounds are more likely to wake us up than quieter ones. For example, a loud bang from someone dropping something in the middle of the night is likely to startle and wake us. On the other hand, we will probably sleep through the sound of a mosquito quietly buzzing nearby. Similarly, the loud ringing of an alarm is more likely to wake us up than a quiet whisper.

The type of sound also matters. Sounds that are either unusual or important to us are more likely to wake us. Our brain interprets unusual sounds as a threat and alerts us to that danger, allowing us to decide if we need to protect ourselves or run away. Our brain is also more likely to wake us up to sounds it considers important, like our name. We will more readily wake when our name is called compared to someone else's name.

Additionally, the depth of our sleep plays a role in how likely we are to wake up to loud noises. When we sleep, we go through cycles consisting of light and deep stages of sleep. We are more easily woken during light sleep than during deep sleep. On average, we have about five to six sleep cycles each night, depending on how long we sleep. We have more deep sleep in the first half of the night and more light sleep in the second half.

Unusual or important sounds are more likely to wake us up

While sleeping, our brains can decide to ignore sounds, movements, and smells that would otherwise wake us. Our ears continue working as usual, but our brain acts as a filter, deciding whether we should wake up or continue sleeping. Louder sounds are more likely to wake us up, but our brains also interpret unusual or important sounds as threats and wake us up to alert us to potential danger.

Our brains are more likely to wake us up if we hear a loud bang in the middle of the night than if we hear a mosquito buzzing. Similarly, we are more likely to wake up if we hear our name being called than if we hear someone else's name.

During light sleep, we are more likely to hear noises around us and wake up. However, during deep sleep, our brains disconnect from the outside world, and we are less likely to hear external sounds or be disturbed by them.

Our brains continue to process sounds while we sleep, and we may even be able to hear and process words. A 2016 study found that during light sleep, participants' brains responded to words and continued verbal recognition tasks started when they were awake. They were even able to hear and process new words. However, during deep sleep, participants' brains stopped processing words and began resting deeply.

Our brains are listening for certain sounds while we sleep, even during deep sleep. We become accustomed to the usual sounds in our environment, such as the hum of the fridge or the heating system turning on and off. However, we wake up almost immediately if we hear a strange or unusual sound.

The brain is more responsive than we think

While we commonly assume that our brains shut off from the outside world during sleep, recent studies have shown that our brains are, in fact, more responsive than we think. During sleep, our brains continue to process sounds in the environment, and even distinguish between different types of sounds.

A 2019 study published in the Human Nature Behavior Journal examined how the brain processes external sound information during sleep. The study found that our brains do pay attention to sounds around us while we sleep, and even process and filter this auditory information. The brain is more responsive to certain sounds than others, and can distinguish between different types of voices and sentences.

The study was designed to mimic the "cocktail party problem", where participants would hear multiple voices at once, similar to being at a party. Researchers played two voices to sleeping participants, one speaking in clear sentences and the other speaking gibberish. Brain activity was monitored using EEG, and researchers found that participants paid more attention to the meaningful voice, indicating that the brain was actively processing and filtering sounds.

This highlights that our brains are indeed responsive to external stimuli during sleep, and can even learn new things during the initial stages of sleep. While we may not consciously remember hearing these sounds when we wake up, our brains are still keeping track of our surroundings.

The responsiveness of the brain varies depending on the stage of sleep. During the initial stages of light sleep, the brain is more active and responsive to external stimuli. As we progress into deeper stages of sleep, the brain's awareness of external sounds diminishes significantly. This is when auditory processing ceases, and we are less likely to be awakened by noises.

Overall, these findings demonstrate that our brains are more responsive during sleep than we previously thought. While we may not consciously perceive our surroundings, our brains actively process sounds and stimuli, protecting our sleep while also ensuring our survival by responding to potential threats.

Hearing loss impacts sleep quality

While asleep, our brains can filter out sounds, deciding whether we should wake up or continue sleeping. However, hearing loss can impact sleep quality, as those with hearing loss will struggle to hear during both the day and at night.

Hearing Loss and Sleep Quality

Hearing loss can negatively impact sleep quality, and this effect is especially pronounced in cases of insomnia. A 2011 study found that hearing impairment was independently associated with sleep disturbance, with a focus on insomnia, in workers exposed to harmful noise. The study also found that tinnitus was the main sleep-disrupting factor, with those affected experiencing a 75% higher score on the Mini Sleep Questionnaire (MSQ).

Sleep Stages and Hearing

The different stages of sleep also play a role in our ability to hear while sleeping. During light sleep, we are more likely to hear noises and wake up. In contrast, during deep sleep, our brains disconnect from the outside world, and we are less likely to hear external sounds or be disturbed by them.

Sleep and Hearing Health

The link between sleep quality and hearing loss is gaining recognition. Sleep duration, in particular, has been found to correlate with hearing ability. Individuals who consistently sleep less than the recommended seven to nine hours per night experience greater numbers of hearing loss episodes. This may be due to reduced time for restorative processes and poor cardiovascular health, which can reduce blood flow to the inner ear, damaging the delicate hair cells responsible for auditory function.

Obstructive Sleep Apnea and Hearing

Obstructive Sleep Apnea (OSA) is a sleep disorder characterised by repeated interruptions in breathing during sleep. OSA has been linked to an increased likelihood of hearing loss due to reduced oxygen in the bloodstream, which can damage inner ear hair cells. Additionally, OSA causes people to wake up throughout the night, contributing to poor or reduced amounts of sleep.

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