A new study reveals that the human brain pays attention to unfamiliar sounds during sleep to stay alert to potential threats.
Researchers in Austria measured the brain activity of sleeping adults in response to familiar and unfamiliar sounds.
Hearing unfamiliar sounds while asleep caused the human brain to ‘tune’ during non-rapid eye movement sleep (NREM), the first stage of sleep.
But the researchers say they didn’t see the effect during REM, the deepest stage of sleep, possibly due to changes in the microstructure of the brain.
WE CONTINUE TO MONITOR THE ENVIRONMENT WHILE SLEEPING
Even though our eyes are closed from those around us, the brain continues to monitor the environment while we sleep, balancing the need to stay asleep with the need to wake up.
One way to achieve this, according to experts, is to selectively respond to unfamiliar sounds rather than familiar ones.
NO RESTful SLEEP
This can be traced back to the long process of human evolution and the need to wake up quickly in the face of potential danger characterized by less familiar auditory cues.
Overall, the study suggests that unfamiliar sounds from the television interfere with a restful night’s sleep as the brain is on higher alert.