This is so that hyenas don’t sneak up and eat us while we are asleep............
This is so that hyenas don’t sneak up and eat us while we are asleep............
~~~
That’s right, actually.
I didn’t need a scientific study to tell me this.
I’ve gotten used to ambient sounds and I don’t need dead silence to sleep. TV, radio, dog barking in the distance, animals moving around the house, cars on the road, even people talking (as long as it’s not loud), and usually even cell phone ringers, I can sleep through. But certain sounds will wake me up, and they don’t all have to be loud, like a door being opened or closed, or an unusual animal sound. Your brain is constantly filtering sounds and identifying them as normal or specific. This doesn’t just happen when you sleep. It happens all day long. Otherwise you’d be distracted constantly. Even house pets filter out the sound from your television set. They know the properties of that sound have no relevance to them, no matter what is being played. Your ears (or auditory functions) don’t shut down. They never do, unless you are fully unconscious, but then again that’s an obvious exception, because if you are fully unconscious, a lot of other cognitive functions are shut down that normally wouldn’t.
It’s not just humans. Just about any animal would need to be able to discern sounds while they sleep, as a matter of survival. Hyena’s included.
I had a couple of dogs asleep on the couch, years ago. I got a hotdog out of the ‘fridge, broke it in half, and placed the pieces by their noses. After a couple of minutes, I whispered “walkies” and they exploded off the couch and ran to the door.
And the rest of us sleep with an AC or air fan on to block out such sounds...