ELI5 Why would most of us awaken to a sudden noise but perhaps less so to a sudden light or aroma?


So, we have 5 basic senses. When we’re asleep, I wondered why a loud noise would likely rouse us whilst a sudden bright light may rouse less of us and even less would probably wake up to a sudden odour.

In: Biology

You can hear a knock on the door when someone visits your house, but you can’t smell them. Also, eyelids.

There was a study done that seemed to prove that people lose their sense of smell when they’re unconscious. That’s why we need smoke alarms instead of just the smell of burning to wake us up.

If you think about it in terms of evolution, a nearby predator is much more likely to cause a sudden noise than a sudden light or aroma. So we have a very good reason to wake up at the first one and none for the latter two.