Can You Hear While Sleeping?

Can You Hear While Sleeping?

Sometimes sleep seems like the sweetest relief at the end of a busy day. Aside from a well-needed rest, regular, healthy sleep hygiene helps boost your immune system, improve heart health, improve focus, and reduce stress. Despite the well-needed break, it provides your body, it also gives your mind a rest. Many people make the mistake that we are our brains are inactive while we rest but aside from dreaming there are stages of sleep where we can hear the world around us while we slumber!

Sleep Stages

The ideal amount of sleep per night ranges between 7 to 9 hours. When we drift off into sleep, it is not a long duration but sectioned into sleep cycles. The sleep cycle consists of four stages which we may experience multiple times throughout the night. Here are the four stages and what is occurring in our brain:

–  Stage 1: The first stage is when we start to fall asleep and lasts around 1 to 5 minutes depending on the level of our exhaustion. It’s the dozing off stage where the body starts to relax, and the brain activity slows. During this stage, it’s easy to be jarred awake but with no disruptions, the body can move on to the next stage.

–  Stage 2:  Lasting around 10-25 minutes at first as the sleep cycles repeat themselves stage two becomes longer. Around half of the time sleeping is in stage 2, in which the body and brain enter a deeper state of relaxation. The body may reduce in temperature and heart rate slows.

–  Stage 3: This is considered the deep stage of sleep where the entire body becomes deeply relaxed. Muscles, heart rate, and breathing decrease. This stage reduces brain activity, allowing it to be a time to replenish and recover for cognitive functioning.

Lasting around 20-40 minutes, this cycle becomes shorter as the night progresses.

–  Stage 4:  The final stage of sleep is known as REM sleep which stands for Rapid Eye Movement. Contrary to stage 3, brain activity increases, nearly equal to when one is fully awake. However, the body remains in a deep state of relaxation, save for the eyes and breathing muscles. This is the stage where people dream most vividly and becomes longer as the night continues.

Hearing While Sleeping

To understand our auditory system while we sleep, a 2019 study, published in the Human Nature Behavior Journal, researched people’s response to sound throughout sleep cycles. Researchers played sounds that replicated what was called “the cocktail party problem”. This emulates the effect of multiple conversations occurring at once and attempting to focus on a particular one. This is a skill that is particularly difficult for hearing impaired people as it’s difficult to prioritize sounds. The researchers attempted to replicate the cocktail party effect by playing two sounds – one in each ear while study participants slept. One voice was clear, saying full sentences and phrases. The other ear played a track of gibberish which could not be understood by anyone. The researchers then used EEG recordings to monitor brain activity throughout the four cycles of sleep.

By the end of the study, researchers determined that the brain was paying attention to the track which contained full sentences and phrases rather than the ear in which gibberish was being played. It seemed that as Thomas Andrillon, lead author of the study described,  “the brain was turning its internal volume up for this particular speaker.”

What Does it Mean?

The purpose of this study was to determine when and how much an individual could hear while they slept. The study proved that the brain does respond to sound even while it sleeps. However, this aligns with particular stages of sleep. In some states such as REM, and stage 1, the brain is more active, than others. The study noted that just because you can hear does not mean you will remember the sounds. Often the sounds become integrated into the dreaming life. Regardless, our brains are constantly taking in audio information. If you are having issues with hearing do not hesitate to reach out to us about a hearing consultation. We can help you hear your best during the day so that your nights can be free to dream and rest.