Sniffing is used by clinicians to assess a person's brain activity, but during REM sleep, our ability to wake up in response to odors is diminished due to sleepatonia, a healthy paralysis that prevents acting out dreams.
Wake-up smelling salts trigger specific neurons in the brain that promote alertness and arousal, similar to a cold shower or sudden surprise. While scents like peppermint can increase attention, caution should be taken when using smelling salts too close to ammonia as it can damage the olfactory pathway.
Some people have a gene that makes them sensitive to a putrid odor within microwave popcorn, causing them to find the smell repulsive.
The type of scents that we find pleasant or unpleasant can be linked to our genetic makeup and the activity of our olfactory neurons, according to a podcast host.