You know how sometimes things that happen in the real world can affect your dreams?  Like you might think fleetingly of someone and then have that person pop up in a dream.  Or a noise like an alarm clock sounding figures in a dream narrative.

Nice Fragrance=Sweet Dreams

Now, dream researchers in Germany have found that odors, too, can affect dreams. Nice smells, like roses, tend to result in happier dreams, while repugnant scents like rotten eggs more often result in bad dreams.

The researchers studied several young women in their twenties, a group known to have the best sense of smell.  While sleeping, the women breathed in air through tubes taped to their nostrils.

REM Study

During REM sleep, when most dreams occur, the subjects received rose-scented air, then rotten egg-scented air, and then plain air.

When awakened a few minutes after the infusion of rose air, nearly all of the women reported having pleasant dreams.  When awakened after receiving the foul-smelling air, most women reported having dreams with a negative cast.

To be clear, none of the women reported actually smelling roses or rotten eggs in their dreams.  The researchers believe that smells influence dreams indirectly by altering the dreamer's emotions.

Limbic System

After all, smell is governed largely by the brain's limbic system, which also controls emotion and behavior. The researchers reason that if smell can influence our emotions when we're awake, it could just as easily affect emotions while we're asleep and in the throes of a dream.