Eli5: Do our survival instincts include any subtleties, as forms of threat detection?


For example: there is a fire growing near you, you are asleep but it wakes your body up when you smell the burning particles, almost as a form of advanced evasion instinct.

Are things like that possible? I’ve had that happen and I usually suck at waking up in the mornings. Although on this day, I awoke within 4 hours and felt my adrenaline going.

In: 5

Yes. Even when you are sleeping parts of your brain are active processing input. Things that pose a danger, will trigger the brain to wake you up and prepare for the fight or flight reaction, part of which is a shot of adrenaline to wake you up and give you that extra energy to survive.

Smelling smoke where there isn’t supposed to be a fire is one example. Another is when you move into a new place and every creak of the floor or water pipes wake you up. After a while the sounds become familiar and the brain recognises it as a non-threat.

When I was in the military I spent three months on an air base. The quarters were literally at the end of the runway. The first week every time a CF-18 landed or took off I was wide awake. After the first week I slept through the noise with no problems.