Sleep is essential for our physical and mental well-being.

It is a period of rest for our body, but as studies suggest, it is also the time when our brain does its work – from consolidating memory, repairing physical stress, boosting the immune system, and regulating the release of hormones to maintaining brain health. Sleep deprivation is associated with several health issues such as fatigue, cognitive decline, and impaired immunity, among others.

But beyond these functions, there are certain aspects and mechanisms of sleep that scientists are still trying to uncover.

How Does Sleep Affect Our Hearing?

One of the things our brain does during sleep is process sensory inputs from the environment, including sound or noise. But what happens after we fall asleep, and how do we process the sounds in our environment while we sleep?.

Research suggests that sleep affects our auditory processing in various ways. During the non-rapid eye movement (NREM) sleep stage, the brain’s sensitivity to sounds is reduced, and it becomes less responsive to external noise.

This is referred to as the ‘sleeping brain’ hypothesis.

The hypothesis proposes that during sleep, the brain filters out the ‘irrelevant’ acoustic signals and prioritizes the sounds that are essential for our survival, such as the sound of an alarm or crying baby, which have been evolutionarily crucial for our survival and protection.

Another critical aspect of auditory processing during sleep is the phenomenon of ‘sleep spindles’.

Sleep spindles are short bursts of high-frequency waves recorded in the electroencephalogram (EEG), which occur during the NREM stage of sleep. They are believed to play a role in consolidating memory, processing of sensory information, and protecting the brain from external disturbances.

Recent research studies have suggested that there may be a correlation between the amplitude of spindles and the level of auditory sensitivity during sleep. This suggests that such spindles could play a role in filtering the noise and protecting the brain from sensory overload.

How Does Sleep Protect Our Dreams?

Dreams are an essential aspect of our sleep, and they occur during the rapid eye movement (REM) stage. Dreams are unique experiences, and while some dreams may sound absurd or unrealistic, they serve a purpose.

Dreams have been studied from different angles, and it is now evident that they play a crucial role in consolidating memories, problem-solving, and emotional regulation.

But what would happen if we were to experience an interruption in our dreams? Studies have shown that interruptions in REM sleep affect our ability to recall our dreams, and when this happens, we get frustrated and feel like we’re missing out on something important. One study conducted at the University of Zurich found that when participants were interrupted during their REM sleep, their emotional regulation was affected, which led to increased negative emotions such as anxiety and nervousness during the day.

However, the question remains: how does our brain protect our dreams from external disturbances? Researchers suggest that the brain creates an ‘internal model’ of the environment during REM sleep, which enables it to distinguish between the external environment and the dream environment. When external stimuli penetrate the dream environment, the brain activates the necessary mechanisms to block out the sound and protect the dream environment. This process is similar to the way the brain filters sounds during NREM sleep.

The Bottom Line

Sleep is essential, and it provides our brain with the necessary rest to function correctly. As we sleep, our brain does vital work such as consolidating memories, processing sensory inputs, regulating hormones, and releasing stress.

However, beyond these functions, there are several mechanisms by which sleep affects our brain, including how it protects our dreams from external disturbances.

The sleep-related phenomena such as ‘sleep spindles’ and ‘internal models’ are some of the areas that scientists are still trying to understand to improve our understanding of sleep’s role in our physical and mental well-being.