We feel obligated to elaborate on that headline. Anyone who has participated in a week-long camp with 5th and 6th-grade boys can attest to the fact that sleeping people are capable of smelling very bad. Yes, it is very possible to be aromatic while in a sleeping state.

“You don’t smell the coffee and wake up; rather you wake up and then smell the coffee.”

— Rachel Herz

Once you are asleep, however, not even the smell of the most unwashed adolescent can arouse you from your slumber. The sleeping brain is unable to process smells.

This is the conclusion of Rachel Herz, a professor of psychiatry at Brown University and author of The Scent of Desire. Her experimental research reveals that when we are in REM sleep or deep sleep, we do not respond to scents.

Not all scientists agree. Thomas Hummel, a professor at the Smell and Taste Clinic of the University of Dresden, concurs that smells are incapable of waking us from our sleep. He believes, however, that the sleeping brain can perceive smells and that they, in turn, can influence our dreams.

He conducted an experiment in which sleeping volunteers were subjected to the rotten-egg smell of hydrogen sulfide and the smell of roses. Participants reported having more positive dreams with the sweet-smelling scents and more negative dreams with the foul-smelling ones.

Herz offers the explanation that when a subject briefly wakes and smells something, the brain will respond if that smell is interesting. As far as the parts of the brain that process smells, however, they are inactive while we are slumbering.

“You cannot smell while you are asleep,” she says. “You don’t smell the coffee and wake up; rather you wake up and then smell the coffee.”

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