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Dream Sense: How Smells Affect Our Dreams

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Have you ever fallen asleep with the television on and then had a dream that you were part of the show? Or gone to sleep after a big fight with your significant other and then had a dream where you were being chased? Or played the slumber party game where you put one girl’s hand in a cup of warm water and tried to make her wet the bed? Scientists have known for a long time that there’s some kind of relationship between our dreams and the sounds and sensations happening around us and most of us have had a dream where some external stimulus—a sight, a sound, a memory—seemed to be an influence. What if different smells can influence our dreams, too? 

Rotten Eggs = Rotten Dreams?
They just might be able to. In a recent German study at the University Hospital, Mannheim, two sleep researchers did an experiment where they wafted different smells under the noses of fifteen women sleeping in a lab (women are ideal for studies on smell, since research has shown that their olfactory senses are notably keener than men’s).

While in REM sleep, the phase where dreams are most likely to occur, each woman in the study was tested three times—once with phenyl ethyl alcohol, a scent resembling roses; once with hydrogen sulfide, which mimics the sulfurous stench of rotten eggs; and once with a neutral scent. A minute after being exposed to the odor, they were woken up and interviewed about their dreams.

Curious Conclusions
What was most interesting was that the women reported that the dreams themselves were not necessarily good or bad—no one had terrible nightmares or dreams about jetting to Hawaii with George Clooney—but the odors very much influenced how the dreams made the women feel. The researchers discovered that upon waking, those who smelled a pleasant scent reported having had pleasant dreams, and those who smelled something bad reported that their dreams corresponded. Although the smells didn’t seem to alter the content of their dreams, it did affect how they felt about them.

If you’re sleeping in a room with a ringing alarm clock or a snoring spouse, it’s common for your brain to incorporate those noises into your dreams, but most of the women in the study didn’t remember having dreams in which there was a particular scent or odor. This interesting fact seems to suggest that there’s something very unique about our sense of smell and the way it’s processed.

This study was very small, and no other researchers have yet attempted to replicate its findings, so it’s hard to determine conclusively whether odors really can affect our dreams. Also, there are many different smells out there to test besides rotten eggs and roses. However, if you regularly have unhappy dreams, maybe it’s not a bad idea to check around your house for hidden smell culprits that might be sabotaging you. At the very least, it’s another good reason to cook a batch of chocolate chip cookies before bed.    


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