What happens while we sleep? Scientists and experts have studied the behavior of the human brain during sleep.
Previously, people believed that the human body remains physically and mentally inactive while sleeping. However, subsequent studies and research claimed that the body and brain continued to function throughout the night, which is essential for health.
Now a latest study tells how humans react to voices, especially ‘unfamiliar’ sounds when they sleep, as Austrian researchers measured the brain activity of sleeping adults to assess how they react to familiar and unfamiliar voices .
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According to the study conducted by researchers from the University of Salzburg and published in the journal J Neurosci, the human brain pays attention to “unknown voices” in order to stay alert to potential threats during sleep.
There are two main types of sleep we go through when we rest: rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. NREM is the first stage of sleep and the study found that during this stage, hearing unfamiliar voices during sleep causes the human brain to “tune into”.
The study sheds light on how the brain continues to monitor the environment we live in while we sleep, even if our eyes are closed.
Overall, the study highlighted how unfamiliar voices – such as those from a television, music, etc. – can prevent a restful and peaceful night’s sleep because, as mentioned, the brain is on high alert and paying attention to voices.
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“Our results highlight differences in brain responses to auditory stimuli based on their relevance to the sleeper,” the team states in their paper.
“The results suggest that voice misrecognition is a strong promoter of brain responses during NREM sleep,” they added.
The researchers recruited 17 volunteers, 14 of whom were women for the study. Their average age was 22 and the volunteers had no reported sleep disturbances. They were fitted with polysomnography devices for a full night’s sleep.