Our body can decide to ignore sounds, movements and smells happening around us which might otherwise wake us. This decision-making mostly happens in our brain. (Image Courtesy: Image by Daniela Dimitrova from Pixabay)
This is a fantastic question, Joanna!
During sleep, our body can decide to ignore sounds, movements and smells happening around us which might otherwise wake us.
This decision-making mostly happens in our brain.
Although our ears continue to work as usual, our brain acts as a filter and decides whether we should respond to the sound and wake up or continue sleeping.
If we wake up, then we can form a memory of having heard the sound, but if we don’t wake up then it’s as though we didn’t hear anything.
This is an extraordinary tool as it protects our sleep so we don’t wake up to everything happening while we sleep.
But it also doesn’t completely shut us off from the outside world which would be terrible for our survival.
Our brain responds to loud sounds
Louder sounds are more likely to wake us up than quieter sounds.
For example, a loud bang from someone dropping something in the middle of the night is likely to startle and wake us.
But we’ll probably sleep through the sound of a mosquito quietly buzzing nearby.
The type of sound matters too
Sounds that are either unusual or important to us are also more likely to wake us.
Our brain interprets unusual sounds as a threat and alerts us to that danger. This allows us to decide if we need to protect ourselves or run away if necessary.
Just imagine how useful and protective this would have been for our ancestors who likely slept in the wild surrounded by dangerous predators, such as lions and tigers!
Luckily, we don’t have to worry about sabre-toothed cats anymore, but it’s still useful to be aware of loud bangs or strange noises while we sleep so we or parents can respond.
Our brain is also more likely to wake us to sounds it considers important like our name.